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PubMed2006

Guanosine 3',5'-bispyrophosphate coordinates global gene expression during glucose-lactose diauxie in Escherichia coli.

Guanosine 3',5'-bispyrophosphate (ppGpp), also known as "magic spot," has been shown to bind prokaryotic RNA polymerase to down-regulate ribosome production and increase transcription of amino acid biosynthesis genes during the stringent response to amino acid starvation. Because many environmental growth perturbations cause ppGpp to accumulate, we hypothesize ppGpp to have an overarching role in regulating the genetic program that coordinates transitions between logarithmic growth (feast) and growth arrest (famine). We used the classic glucose-lactose diauxie as an experimental system to investigate the temporal changes in transcription that accompany growth arrest and recovery in wild-type Escherichia coli and in mutants that lack RelA (ppGpp synthetase) and other global regulators, i.e., RpoS and Crp. In particular, diauxie was delayed in the relA mutant and was accompanied by a 15% decrease in the number of carbon sources used and a 3-fold overall decrease in the induction of RpoS and Crp regulon genes. Thus the data significantly expand the previously known role of ppGpp and support a model wherein the ppGpp-dependent redistribution of RNA polymerase across the genome is the driving force behind control of the stringent response, general stress response, and starvation-induced carbon scavenging. Our conceptual model of diauxie describes these global control circuits as dynamic, interconnected, and dependent upon ppGpp for the efficient temporal coordination of gene expression that programs the cell for transitions between feast and famine.

Bacterial Proteins↗
PubMed1997

Interleukin-4 and listeriosis.

Experimental infection of mice with Listeria monocytogenes (L. monocytogenes) has served as an appropriate model for analyzing Th1-cell-driven immune responses. Generally, Th2 responses are absent and IL-4 is not detectable. Here, we describe experimental settings under which IL-4 is detectable in listeriosis. Our data suggest that IL-4 is rapidly produced after infection. This prompt IL-4 burst seems to stimulate chemokine responses and, therefore, may participate in the regulation of the early antilisterial host response. Soon thereafter, IL-4 production wanes. At least partially this seems to be caused by downregulation of IL-4-producing CD4+ NK1+ TCR alpha beta int lymphocytes by IL-12. In the absence of IFN-gamma responsiveness, IL-4 production is demonstrable during acquired immunity against L monocytogenes, and this elevated IL-4 production apparently contributes to disease exacerbation. In conclusion, the data are consistent with a detrimental role of IL-4 in listeriosis and active control of IL-4 synthesis by the antilisterial immune response. The rapid, but transient, IL-4 burst in listeriosis probably contributes to host defense without impairing development of the acquired T-cell response because of its shortness.

Animals↗
PubMed1986

Diurnal variation in neuroendocrine response to stress in rats: plasma ACTH, beta-endorphin, beta-LPH, corticosterone, prolactin and pituitary cyclic AMP responses.

The effects of restraint stress applied at different times of the day on levels of five stress-responsive plasma hormones (ACTH, beta-endorphin, beta-LPH, corticosterone and prolactin) and pituitary cyclic AMP levels were assessed. Different groups of rats were subjected to 15 min of restraint stress at 2-hour intervals over a 24-hour period. Rats were sacrificed immediately upon removal from their home cage (controls) or immediately following restraint (stressed). The time of day of stress exposure markedly affected the stress responses measured. Generally, responses to stress applied at the beginning of the dark cycle (18:00) were less than those seen following stress applied at the beginning of the light cycle (06:00). Stress at 06:00 increased levels of pituitary cyclic AMP 10-fold, while stress applied at 18:00 did not significantly increase pituitary cyclic AMP levels. In stressed rats, high correlations were seen among levels of hormones derived from the common precursor, proopiomelanocortin (ACTH, beta-endorphin, beta-LPH) and between these hormones and levels of pituitary cyclic AMP. These findings support the hypothesis that pituitary cyclic AMP is involved in the stress-induced release or synthesis of the pituitary hormones ACTH, beta-endorphin, and beta-LPH.

Adrenocorticotropic Hormone↗
PubMed2006

Location matters: why target location impacts performance in orientation tasks.

This research explores human performance in a spatial orientation task. In three experiments, participants saw a target highlighted in a visual scene and were asked to locate it on a map of the space. Across all of the experiments, the target's location in the visual scene influenced the participants' response times. Generally, response times increased when the target was located farther away from the viewer, when the target was farther to one side or the other, and when more distractors were nearby. However, there were important exceptions to these findings, suggesting that participants encode the location of a target hierarchically, using different features of the space depending on the target's particular location. We conclude that participants perform such tasks by extracting a description from the egocentric view and then transforming that description to allow them to find the target on the map.

Adult↗
PubMed1985

Combining psychodynamic and behavioral treatment approaches in the treatment of hospitalized adolescents.

This article describes a treatment approach for hospitalized adolescents which attempts to address the "response generalization" problem encountered with behaviorally based treatment milieus. The program is described and preliminary data is given to support its techniques. The treatment program attempts to combine behavioral/objective techniques that are so effective in program management, with subjective/clinical strategies.

Adolescent↗
PubMed2003

Pollutant-specific and general lysosomal responses in digestive cells of mussels exposed to model organic chemicals.

The present study was carried out to elucidate whether lysosomal size reduction in digestive cells of mussels Mytilus galloprovincialis constitutes a selective response against a particular group of organic chemical compounds, in contrast to the lysosomal enlargement characteristic of general stress response. Mussels were treated with di(2-ethylhexyl) phthalate (DEHP), benzo(a)pyrene (B[a]P), and the water accommodated fraction (WAF) of a lubricant oil, which were daily applied by either injection through the adductor muscle for 7 days or water-exposure for 21 days. Control mussels were either kept untreated in clean sea water, or treated with acetone (injection and water-exposure), vehicle used for DEHP and B[a]P. A third set of controls consisted of mussels with pierced shell kept in clean seawater. Digestive glands were excised at various treatment days and beta-glucuronidase activity was demonstrated in 8-microm cryotome sections. Lysosomal volume, surface and numerical densities, and surface-to-volume ratio were quantified by image analysis. Other sections were stained with oil red 0 to demonstrate neutral lipids and changes in lipid levels were quantified by image analysis. Neutral lipid accumulation in digestive cells was used as a complementary indication of exposure to organic chemicals. It resulted to be a very prompt and all-or-nothing response, which reached a plateau before 1 day of treatment with WAF, DEHP and B[a]P after both injection and water-exposure. DEHP-treatment induced a general stress response characterised by lysosomal enlargement in digestive cells, which was already induced after 1 day. Treatment with either WAF or B[a]P elicited a comparable biphasic response. A transient lysosomal enlargement, shorter with WAF than with B[a]P treatment, was evidenced after both injection and water-exposure. Further, under water-exposure conditions, WAF reduced the endo-lysosomal system in size more markedly than B[a]P. Such lysosomal size reduction constitutes a transient response after exposure to diverse organic xenobiotics (acetone, WAF and B[a]P). In addition, this lysosomal size reduction might be followed by a further lysosomal enlargement, which later might yet again give rise to an apparent lysosomal size reduction under chronic exposure conditions. As a whole, the lysosomal response is intricate and cannot be simply interpreted in environmental pollution monitoring programmes. Nevertheless, it still constitutes a powerful and sensitive biomarker extremely useful as early-warning signal.

Analysis of Variance↗
PubMed1991

Sensitivity and transduction mechanisms of responses to general odorants in turtle vomeronasal system.

(a) The responses of the vomeronasal organ to general odorants in the turtle, Geoclemys reevesii, were measured by recording the accessory olfactory bulbar responses. The threshold concentrations of the vomeronasal responses to various odorants were similar to those in main olfactory bulbar responses, indicating that vomeronasal cells lacking cilia and olfactory cells having many cilia have similar sensitivities to general odorants. (b) The vomeronasal epithelium was perfused with 100 mM NaCl solution and the salt-free solution and the effects of NaCl on the vomeronasal responses to various odorants were examined. There was no essential difference between the concentration-response curves for n-amyl acetate and menthone dissolved in 100 mM NaCl solution and those dissolved in the salt-free solution in the whole concentration range examined. The ratios of the magnitudes of vomeronasal responses in the salt-free solution to those in 100 mM NaCl solution were between 1.01 and 1.10 for seven odorants tested. (c) The magnitudes of responses to the odorants were unchanged by changes in NaCl concentrations. The replacement of Na+ with organic cations such as choline+, Bis-Tris propane2+, and N-acetyl-D-glucosamine+ did not affect the magnitudes of the responses to the odorants. The Na channel blocker amiloride also did not affect the responses. (d) The vomeronasal responses were practically unchanged by changes in CaCl2 concentration. The Ca channel blockers diltiazem and verapamil did not affect the responses. (e) The replacement of Cl- with SO4(2-) did not affect the magnitudes of the vomeronasal responses. (f) The present results suggest that ion transport across the apical membranes of vomeronasal receptor cells does not contribute to the responses to odorants in the turtle.

Amiloride↗
PubMed1990

General practitioner response to elderly patients discharged from hospital.

OBJECTIVE: To determine the effect of discharge information given to general practitioners on their management of newly discharged elderly patients. DESIGN: A random sample of 133 elderly patients who had unplanned readmission to a district general hospital within 28 days of discharge was compared with a matched control sample of patients who were not readmitted. Information was gathered from the hospital, the patients, the carers, and the general practitioners about the information that the hospital had sent the general practitioner and the general practitioners' response to this information. SETTING: All specialties in a district general hospital. PATIENTS: 266 Patients aged over 65 representative in the main demographic indices of the population of elderly patients admitted to hospital. RESULTS: Ten weeks after discharge the doctors had received notice of discharge about 169 of the patients, but fewer than half the discharge notices were received within the first week. General practitioners were dissatisfied with the information in 60 cases. A general practitioner visited 174 of the patients after their discharge from hospital and three quarters of the visits took place within two weeks of the discharge. These visits were more likely to have been initiated by patients or families than by the doctor, and this was not influenced by the doctor receiving notice of the patient's discharge. Older patients and those who had carers were the most likely to be visited. Nearly half of the carers were dissatisfied with some aspect of general practitioner care, problems with home visiting being the commonest source of complaint. CONCLUSIONS: Hospital communications to general practitioners about the discharge of elderly patients still cause concern, particularly in the time they take to arrive. Written instruction to vulnerable elderly patients asking them to inform their general practitioner of the discharge might be helpful. Carers complained of lack of support, and it is clearly important for someone (either the general practitioner or another health worker) to visit elderly people shortly after their discharge.

Aged↗
PubMed2005

Genome-wide analysis of the general stress response network in Escherichia coli: sigmaS-dependent genes, promoters, and sigma factor selectivity.

The sigmaS (or RpoS) subunit of RNA polymerase is the master regulator of the general stress response in Escherichia coli. While nearly absent in rapidly growing cells, sigmaS is strongly induced during entry into stationary phase and/or many other stress conditions and is essential for the expression of multiple stress resistances. Genome-wide expression profiling data presented here indicate that up to 10% of the E. coli genes are under direct or indirect control of sigmaS and that sigmaS should be considered a second vegetative sigma factor with a major impact not only on stress tolerance but on the entire cell physiology under nonoptimal growth conditions. This large data set allowed us to unequivocally identify a sigmaS consensus promoter in silico. Moreover, our results suggest that sigmaS-dependent genes represent a regulatory network with complex internal control (as exemplified by the acid resistance genes). This network also exhibits extensive regulatory overlaps with other global regulons (e.g., the cyclic AMP receptor protein regulon). In addition, the global regulatory protein Lrp was found to affect sigmaS and/or sigma70 selectivity of many promoters. These observations indicate that certain modules of the sigmaS-dependent general stress response can be temporarily recruited by stress-specific regulons, which are controlled by other stress-responsive regulators that act together with sigma70 RNA polymerase. Thus, not only the expression of genes within a regulatory network but also the architecture of the network itself can be subject to regulation.

Bacterial Proteins↗
PubMed2004

General stress response regulator RpoS in adaptive mutation and amplification in Escherichia coli.

Microbial cells under growth-limiting stress can generate mutations by mechanisms distinct from those in rapidly growing cells. These mechanisms might be specific stress responses that increase mutation rates, potentially altering rates of evolution, or might reflect non-stress-specific processes in rare growing cells. In an Escherichia coli model system, both frameshift reversion mutations and gene amplifications occur as apparent starvation-induced mutations. Whereas frameshift reversion ("point mutation") requires recombination proteins, the SOS response, and error-prone DNA polymerase IV (DinB), amplification requires neither SOS nor pol IV. We report that both point mutation and amplification require the stationary-phase and general stress response transcription factor RpoS (sigmaS). Growth-dependent mutation does not. Alternative interpretations are excluded. The results imply, first, that point mutation and amplification are stress responses that occur in differentiated stationary-phase (not rare growing) cells and, second, that transient genetic instability, producing both point mutation and genome rearrangement, may be a previously unrecognized component of the RpoS-dependent general stress response.

Adaptation, Biological↗
PubMed2004

Specific growth rate and not cell density controls the general stress response in Escherichia coli.

In batch cultures of Escherichia coli, the intracellular concentration of the general stress response sigma factor RpoS typically increases during the transition from the exponential to the stationary growth phase. However, because this transition is accompanied by complex physico-chemical and biological changes, which signals predominantly elicit this induction is still the subject of debate. Careful design of the growth environment in chemostat and batch cultures allowed the separate study of individual factors affecting RpoS. Specific growth rate, and not cell density or the nature of the growth-limiting nutrient, controlled RpoS expression and RpoS-dependent hydroperoxidase activity. Furthermore, it was demonstrated that the standard E. coli minimal medium A (MMA) is not suitable for high-cell-density cultivation because it lacks trace elements. Previously reported cell-density effects in chemostat cultures of E. coli can be explained by a hidden, secondary nutrient limitation, which points to the importance of medium design and appropriate experimental set-up for studying cell-density effects.

Bacterial Proteins↗
PubMedDate not supplied

Clinical interpretations of transient otoacoustic emissions.

PURPOSE: The purpose of this study was to characterize the relation of different ordinal patterns of transient otoacoustic emissions (TEOAES) with respect to underlying otologic disorders and auditory status. PATIENTS AND METHODS: The results of TEOAEs in 225 patients with various auditory disorders were investigated and compared with normative data established from 90 subjects of various ages. TEOAEs were categorized according to four patterns: (1) normal (general response level within 90% of normative data, (2) reduced amplitude (general response level was > or =2 dB peak sound pressure level (pSPL), but less than the mean -1.64 SD of the normative data), (3) abnormal morphology of frequency spectrum (general response level was within normal limits, but reduced at > or =2 individual octave frequencies between 1,000 and 5,000 Hz), and (4) total absence (response level <2 dB pSPL). RESULTS: This study showed that the normal pattern of TEOAEs, in terms of response amplitude, varied with age. Our results further indicated that a reduced amplitude pattern of TEOAEs was noted in patients with a mild sensorineural hearing loss (SNHL), negative tympanometric pressure, a pressure-equalization tube, and Meniere's disease. TEOAEs provided good frequency-specific information for patients with a noise-induced hearing loss. All patients with ossicular chain abnormalities, more than moderate SNHL, and a middle ear mass or effusion had total absence of TEOAEs. Patients with acoustic neuroma and brainstem lesions presented a complex profile of TEOAEs. In the follow-up of auditory function in patients undergoing otologic surgery, different patterns of TEOAEs between the preoperative and postoperative recordings were evident, which correlated with the hearing thresholds and middle ear status. The abnormal findings of TEOAEs due to specific auditory diseases were discussed. CONCLUSION: The interpretation of TEOAEs can be facilitated through an analysis of specific patterns and in combination with other audiologic tests.

Acoustic Impedance Tests↗
PubMed2001

Atypical presentation of dopa-responsive dystonia: generalized hypotonia and proximal weakness.

Dopa-responsive dystonia (DRD) is an autosomal dominant disorder typically presenting as dystonia with diurnal variability. Described is an 8-year-old boy who had had waddling gait, generalized hypotonia, and proximal weakness since early childhood. He responded well to low-dose L-dopa. He had a point mutation of the GTP cyclohydrolase I gene. The patient's father and sister had the same mutation but did not have proximal weakness. GTP cyclohydrolase I deficiency can present with hypotonia and weakness.

Carbidopa↗
PubMed2000

Cell injury releases endogenous adjuvants that stimulate cytotoxic T cell responses.

General immunostimulants (adjuvants) are essential for generating immunity to many antigens. In bacterial infections, adjuvants are provided by components of the microorganism, e.g., lipopolysaccharide. However, it is unclear what provides the adjuvant effect for immune responses that are generated to tumors and many viruses. Here we show that cell injury and death of tumor or even normal cells provide a potent adjuvant effect for the stimulation of cytotoxic T lymphocyte responses. This adjuvant activity is constitutively present in the cytoplasm of cells and is increased in the cytoplasm of cells dying by apoptosis. The release of these components stimulates immune responses both locally and at a distance, and provides a simple mechanism to alert the immune system to potential danger in almost all pathological situations.

3T3 Cells↗
PubMed2001

Global analysis of the general stress response of Bacillus subtilis.

Gene arrays containing all currently known open reading frames of Bacillus subtilis were used to examine the general stress response of Bacillus. By proteomics, transcriptional analysis, transposon mutagenesis, and consensus promoter-based screening, 75 genes had previously been described as sigma(B)-dependent general stress genes. The present gene array-based analysis confirmed 62 of these already known general stress genes and detected 63 additional genes subject to control by the stress sigma factor sigma(B). At least 24 of these 125 sigma(B)-dependent genes seemed to be subject to a second, sigma(B)-independent stress induction mechanism. Therefore, this transcriptional profiling revealed almost four times as many regulon members as the proteomic approach, but failure of confirmation of all known members of the sigma(B) regulon indicates that even this approach has not yet elucidated the entire regulon. Most of the sigma(B)-dependent general stress proteins are probably located in the cytoplasm, but 25 contain at least one membrane-spanning domain, and at least 6 proteins appear to be secreted. The functions of most of the newly described genes are still unknown. However, their classification as sigma(B)-dependent stress genes argues that their products most likely perform functions in stress management and help to provide the nongrowing cell with multiple stress resistance. A comprehensive screening program analyzing the multiple stress resistance of mutants with mutations in single stress genes is in progress. The first results of this program, showing the diminished salt resistance of yjbC and yjbD mutants compared to that of the wild type, are presented. Only a few new sigma(B)-dependent proteins with already known functions were found, among them SodA, encoding a superoxide dismutase. In addition to analysis of the sigma(B)-dependent general stress regulon, a comprehensive list of genes induced by heat, salt, or ethanol stress in a sigma(B)-independent manner is presented. Perhaps the most interesting of the sigma(B)-independent stress phenomena was the induction of the extracytoplasmic function sigma factor sigma(W) and its entire regulon by salt shock.

Bacillus subtilis↗
PubMed1997

The long-term effects of functional communication training in home settings.

A four-phase study was conducted in the homes of 4 young children who displayed aberrant behavior. Phases 1 and 2 consisted of a series of descriptive and experimental analyses to identify the environmental antecedents and consequences that controlled aberrant behavior. Phases 3 and 4 evaluated the short- and long-term effects of treatment on aberrant behavior, target mands, and collateral (social and toy play) behaviors. The effects of treatment were monitored for up to 27 months to assess long-term suppression of aberrant behavior. The assessment results successfully identified environmental events that occasioned and maintained aberrant behavior for all children. The short-term treatment resulted in immediate decreases in aberrant behavior for 3 of 4 children. Long-term treatment was successful for all children and was correlated with substantial response generalization. These results are interpreted in relation to functional equivalence, pivotal responding, and response generalization.

Behavior Therapy↗
PubMed2000

Cellular lipid composition influences stress activation of the yeast general stress response element (STRE).

The heat inducibility of the yeast heat-shock response (HSR) pathway has been shown to be critically dependent on the level of unsaturated fatty acids present in the cell. Here the inducibility by heat or salt of the independently regulated general stress response (GSR) pathway is shown to be affected in the same way. An increase in the percentage of unsaturated fatty acids in heat- or salt-acclimated cells correlated with a decrease in the induction of a general stress-response-promoter-element (STRE)-driven reporter gene by either stress. Despite inducing reporter gene expression, sorbic acid treatment did not confer salt cross-tolerance on the cells. This failure correlated with a failure to increase the percentage of unsaturated fatty acids in the cells, suggesting that GSR pathway induction, in the absence of lipid changes, is insufficient for the induction of cross-tolerance. Cells grown with fatty acid supplements under anaerobic conditions provided further evidence for a potential role for lipids in the acquisition of stress resistance. These cells contained different fatty acid profiles depending on the fatty acid supplement supplied, exhibited differential sensitivity to both heat and salt stress, but had not undergone STRE induction. These results suggest that heat- and salt-stress induction of the GSR are sensitive to the level of unsaturated fatty acids present in the cell and that stress cross-tolerance may be a lipid-mediated phenomenon. Given that an increased level of unsaturated fatty acids also down-regulates heat induction of the HSR pathway, these observations lead to the provocative hypothesis that lipid modifications, rather than HSR or GSR pathway induction, are a major contributor to the induced heat and salt tolerance of yeast cells.

Adaptation, Biological↗