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'.

Associations between early alcohol and tobacco use and prolonged time to puberty in boys.

BACKGROUND: Previous research has demonstrated a relationship between prepubertal alcohol and tobacco use and delayed pubertal characteristics in girls. Although, laboratory research indicates that alcohol and tobacco use inhibits sexual maturation in male rats, human research in this area is lacking. To address this question among boys, we conducted a study to explore the association between early use of alcohol and tobacco and time to development of secondary sexual characteristics. METHODS: The study population included 3199 boys interviewed between the ages of 11 and 21. Participants reported the ages at which they first experienced body hair growth, deepening of the voice and facial hair growth. Early alcohol and tobacco use were defined as first use preceding the age of pubertal development among those reporting regular consumption patterns. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox proportional hazard models. RESULTS: Early alcohol use was associated with longer time to body hair growth (HR 0.77; 95% CI 0.69-0.87), voice changes (HR 0.72; 95% CI 0.64-0.82) and facial hair growth (HR 0.77; 95% CI 0.68-0.86), after adjusting for tobacco use and age at interview. Tobacco use was not independently associated with the puberty indicators after controlling for alcohol use and age at interview. CONCLUSIONS: Our findings are consistent with the hypothesis that alcohol may inhibit puberty onset in boys, an association that has been previously observed among young girls. Thus, alcohol may be an exposure deserving more scrutiny as a disruptor to normal pubertal development.

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.

Upper limits on perturbations of nuclear decay rates induced by reactor electron antineutrinos.

We report the results of an experiment conducted near the High Flux Isotope Reactor of Oak Ridge National Laboratory, designed to address the question of whether a flux of reactor-generated electron antineutrinos (ν¯e) can alter the rates of weak nuclear interaction induced decays of 54Mn, 22Na, and 60Co. This experiment has small statistical errors but, when systematic uncertainties are included, has null results. Perturbations greater than one part in 104 are excluded at 95% confidence level in ß± decay and electron capture processes, in the presence of an antineutrino flux of 3 × 1012 cm-2s-1. The present experimental methods are applicable to a wide range of radionuclides. Improved sensitivity in future experiments can be anticipated as we continue to better understand and reduce the dominant systematic uncertainties.

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.

Complement and immunoglobulins stimulate superoxide production by human leukocytes independently of phagocytosis.

Human peripheral blood polymorphonuclear leukocytes, when exposed to appropriate stimuli, generate significant amounts of superoxide anion (O-.2), a highly reactive molecule which is possibly involved in bacterial killing. Since the subcellular localization and mechanism of activation of O-.2 generating systems are unknown, we have investigated superoxide dismutase-inhibitable cytochrome c reduction (attributable to O-.2) by, and lysosomal enzyme release from, normal polymorphonuclear leukocytes and cells rendered incapable of ingesting particles by treatment with cytochalasin B. Neither phagocytosis nor lysosomal degranulation were prerequisites for enhanced O-.2 generation. Cytochalasin B-treated cells exposed to (a) serum-treated zymosan, a C3b receptor stimulus; (b) heat aggregated human IgG, an Fc receptor stimulus; and (c) the complement component, C5a, generated enhanced amounts of O-.2 in a time and concentration-dependent fashion. These cells also responded by releasing lysosomal enzymes, but there was no correlation between the ability of any immune reactant to provoke enzyme release and its ability to stimulate O-.2 generation. The three stimuli also enhanced O-.2 generation by normal (untreated) polymorphonuclear leukocytes, but only serum-treated zymosan and aggregated IgG were capable of provoking lysosomal enzyme release from normal cells. Untreated zymosan and native IgG neither stimulated O-.2 production nor provoked lysomal enzyme release. Since enhanced O-.2 production was stimulated by immune reactants in the absence of phagocytosis, the O-.2 generating system is very likely associated with the external plasma membrane of the polymorphonuclear leukocyte. Leukocyte membrane receptors for complement and immunoglobulins may therefore not only serve in particle recognition but also may initiate biochemical events which accompany phagocytosis and killing.

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.

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.

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.

Hopelessness and attempted suicide: a reconsideration.

The authors administered measures of depression, hopelessness, and strength of suicidal intent to a sample of 112 suicide attempters. The results for the 55 subjects diagnosed as depressive and admitted within 72 hours after their attempt were compared with results obtained by Minkoff and associates using comparable measures. Contrary to the findings of the earlier study, there was a lower correlation between hopelessness and intent than between depression and intent. The authors suggest that demographic differences between the two samples may provide explanations for this descrepancy, in the that they reflect the presence or absence of external societal supports that may influence the suicidogenic potential of hopelessness.

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.

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.

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.

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.

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.

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.

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.

Influence of corticosteroids on human polymorphonuclear leukocyte function in vitro : Reduction of lysosomal enzyme release and superoxide production.

In an experimental system in which phagocytosis or adherence of cells to surfaces were excluded as variables, we have investigated the possibility that corticosteroids may inhibit release of lysosomal constituents from viable human polymorphonuclear leukocytes into the extracellular environment. Release ofΒ-glucuronidase and lysozyme from cytochalasin B-treated cells exposed to serum-treated zymosan, heat-aggregated human IgG, and the complement component C5a was significantly reduced by pretreatment with hydrocortisone sodium succinate and methylprednisolone sodium succinate (5×10(-4) M). Both steroids also reduced superoxide production by these cells. These in vitro studies provide evidence that corticosteroids influence membrane-dependent responses of intact, viable polymorphonuclear leukocytes to immune reactants. Inhibition of these responses (lysosomal enzyme release, superoxide production) may explain, in part, both the antiinflammatory actions of steroids and their deleterious effects on host defenses.

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.