Incubation periods of enteric illnesses in foodborne outbreaks, United States, 1998-2013.

Early in a foodborne disease outbreak investigation, illness incubation periods can help focus case interviews, case definitions, clinical and environmental evaluations and predict an aetiology. Data describing incubation periods are limited. We examined foodborne disease outbreaks from laboratory-confirmed, single aetiology, enteric bacterial and viral pathogens reported to United States foodborne disease outbreak surveillance from 1998-2013. We grouped pathogens by clinical presentation and analysed the reported median incubation period among all illnesses from the implicated pathogen for each outbreak as the outbreak incubation period. Outbreaks from preformed bacterial toxins (Staphylococcus aureus, Bacillus cereus and Clostridium perfringens) had the shortest outbreak incubation periods (4-10 h medians), distinct from that of Vibrio parahaemolyticus (17 h median). Norovirus, salmonella and shigella had longer but similar outbreak incubation periods (32-45 h medians); campylobacter and Shiga toxin-producing Escherichia coli had the longest among bacteria (62-87 h medians); hepatitis A had the longest overall (672 h median). Our results can help guide diagnostic and investigative strategies early in an outbreak investigation to suggest or rule out specific etiologies or, when the pathogen is known, the likely timeframe for exposure. They also point to possible differences in pathogenesis among pathogens causing broadly similar syndromes.

Analysis of non-destructive current simulators of flux compression generators.

Development and evaluation of power conditioning systems and high power microwave components often used with flux compression generators (FCGs) requires repeated testing and characterization. In an effort to minimize the cost and time required for testing with explosive generators, non-destructive simulators of an FCG's output current have been developed. Flux compression generators and simulators of FCGs are unique pulsed power sources in that the current waveform exhibits a quasi-exponential increasing rate at which the current rises. Accurately reproducing the quasi-exponential current waveform of a FCG can be important in designing electroexplosive opening switches and other power conditioning components that are dependent on the integral of current action and the rate of energy dissipation. Three versions of FCG simulators have been developed that include an inductive network with decreasing impedance in time. A primary difference between these simulators is the voltage source driving them. It is shown that a capacitor-inductor-capacitor network driving a constant or decreasing inductive load can produce the desired high-order derivatives of the load current to replicate a quasi-exponential waveform. The operation of the FCG simulators is reviewed and described mathematically for the first time to aid in the design of new simulators. Experimental and calculated results of two recent simulators are reported with recommendations for future designs.

The Appropriateness Evaluation Protocol is a poor predictor of in-hospital mortality.

BACKGROUND: The Appropriateness Evaluation Protocol (AEP) proposes admission criteria based only on physiological and laboratory parameters and has recently informed an Irish national bed utilisation review. Severity of illness tools can be poorly predictive of outcomes, particularly in older patients. AIMS: To assess the clinical utility of the AEP in moribund older and younger patients. METHODS: The study was conducted in four acute hospitals in South Munster, Ireland, and was of retrospective analytical cohort study design. The Hospital In-Patient Enquiry Scheme was used to ascertain patients who died within 10 days of hospital admission, over a 2-year period. Proximate death was used as a robust measure of validity of admission. Emergency department (ED) records were screened retrospectively to allocate the AEP criteria. RESULTS: There were 803 eligible in-hospital deaths. Establishment of AEP criteria was available in 72.9 % (585 patients, 50.8 % female). The median length of stay until death was 4 days. Just over 30 % (179/585) of patients did not meet AEP criteria, two-fifths (72/179) of whom had been coded as severely unwell on arrival to the ED. There was no significant difference in AEP identification rates between older and younger age groups. CONCLUSIONS: Our study illustrates that the AEP is a poor predictor of mortality in all age groups, having failed to identify approximately one-third of our cohort. Based on our findings, we feel that this tool should not be used to assess the appropriateness of admission.

Predictors of early arrival at the emergency department in acute ischaemic stroke.

BACKGROUND: A requirement of an effective acute stroke service is the early arrival of patients to the hospital emergency department (ED). This will allow the possible use of thrombolytic therapy or other acute interventions within a limited time window. AIMS: We investigated the predictors of early arrival in a single hospital serving a mixed urban and rural catchment area. METHODS: A retrospective review of all case notes for 1 year was performed. RESULTS: Of 105 acute strokes, 91 were cerebral infarcts and a total of 71 cases presenting initially to the ED had timing available for analysis. 39.4% presented within 3 h, and 12.7% were potentially suitable for thrombolysis. Those living closer to the hospital were not more likely to arrive within 3 h (Z = -0.411, p = 0.68). Presenting directly to the hospital by emergency services (or private transport) was significantly associated with early arrival in a univariate comparison (p < 0.001), and in a multivariate model. CONCLUSION: The only independent predictor of early arrival to the ED is direct presentation. Improved public education of the importance of recognition of stroke symptoms and rapid contact with the emergency services will improve the early attendance following acute stroke, allowing increased use of acute stroke treatments.

Inappropriate prescribing in the elderly: a comparison of the Beers criteria and the improved prescribing in the elderly tool (IPET) in acutely ill elderly hospitalized patients.

BACKGROUND: In appropriate prescribing is a significant and persistent problem in elderly people, both in hospital and the community and has been described in several countries in Europe and also the USA. The problem of inappropriate prescribing has not been quantified in the Republic of Ireland. The most commonly used criteria for the identification of inappropriate prescribing are the Beers' criteria [both independent of diagnosis (ID) and considering diagnosis (CD) - 2003 version]. The Beers' criteria ID includes 48 different categories of either single medications or multiple medications of a similar class identified as inappropriate prescriptions and the Beers' criteria CD contains 19 different categories containing possible drug-disease interactions. A second tool, the improved prescribing in the elderly tool (IPET) has also been validated and used in hospital and community studies and has 14 categories of either explicitly contraindicated medications or possible drug-disease interactions. OBJECTIVES: The primary aim of the study is to measure the incidence of inappropriate prescribing among older community-dwelling individuals presenting to an acute hospital in the Republic of Ireland. A secondary aim of this study was also therefore to compare the efficacy of the above two tools in identifying inappropriate prescribing. METHODS: A prospective, consecutive observational cohort study was carried out over a 4-month period. The setting was an urban-based university hospital acute geriatric medicine assessment unit. Subjects in this study (n = 350) were consecutively screened on admission to hospital (mean age = 80.3 +/- 6.1 years) and all patients had both Beers' criteria ID and CD and IPET applied to their list of prescription drugs on admission, cross-referenced with their list of current active medical diagnosis. RESULTS: The results of the study identified a high rate of inappropriate prescribing among this population of community-dwelling subjects. The total number of inappropriate prescriptions identified using the Beers' criteria (ID) was 148 affecting 121 patients. The Beers' criteria (CD) identified 69 inappropriate prescriptions in 60 patients and the IPET identified 112 inappropriate prescriptions in 78 patients. The Beers criteria (ID and CD combined) identified at least one inappropriate prescription in 34% of subjects and the IPET identified one in at least 22% of subjects. CONCLUSIONS: This study identifies high rates of use of inappropriate medications in community-dwelling elderly presenting with acute illness to hospital. These are comparable with inappropriate prescribing rates identified in previous studies. The revised Beers' criteria (2003) identified more inappropriate prescriptions than the IPET in this population of elders.

The pattern of plasma sodium abnormalities in an acute elderly care ward: a cross-sectional study.

INTRODUCTION: The combination of ageing, illness, and medications can lead to hyponatraemia or hypernatraemia. AIMS: To describe the distribution of plasma sodium levels in older patients admitted to hospital. METHODS: We carried out a hospital based cross-sectional study examining 1,511 serum sodium concentrations ([Na+]) among 336 elderly patients and attempted to elucidate the cause(s) of the abnormal serum [Na+]. RESULTS: The study population had a mean age of 81.4. Ninety-two (27.4%) patients had hyponatraemia and seven patients (2.1%) had hypernatraemia during their hospitalisation. The distribution of [Na+] results was towards the lower end of the normal range. The mortality rate of patients with hyponatraemia was 14.1% and that of patients with normal serum [Na+] was 8.9%. Six patients with hypernatraemia died in hospital. Lower respiratory tract infection and medication accounted for the majority of cases. CONCLUSIONS: Deranged [Na+] is common among elderly patients admitted to hospital.

Specific and time-dependent effects of glucocorticoid receptor agonist RU28362 on stress-induced pro-opiomelanocortin hnRNA, c-fos mRNA and zif268 mRNA in the pituitary.

This study examined the effects of the glucocorticoid receptor (GR) agonist RU28362 on stress-induced gene expression in the pituitary of rats to investigate mechanisms of glucocorticoid negative feedback in vivo. In an initial experiment, acute restraint stress produced rapid (within 15 min) induction of c-fos mRNA, zif268 mRNA and pro-opiomelanocortin (POMC) hnRNA within the anterior and intermediate/posterior pituitary as determined by quantitative real-time polymerase chain reaction. Treatment with RU28362 (150 microg/kg, i.p.) 60 min before restraint inhibited adrenocorticotrophic hormone (ACTH) and corticosterone secretion and selectively suppressed the stress-induced increase in POMC hnRNA in the anterior pituitary gland. The failure of RU28362 to surpress the stress-induced rise in c-fos and expression of zif268 mRNA suggests that the central release of ACTH secretagogues was not affected at this time point by treatment with the GR agonist. Rather, the inhibition of ACTH release appeared to be due to a direct effect of RU28362 within the pituitary. A follow-up time-course study varied the interval (10, 60 or 180 min) between RU28362 pretreatment and the onset of restraint. The stress-induced increase in POMC hnRNA was completely blunted by RU28362 treatment within 10 min of treatment, although the stress induced hormone secretion, c-fos mRNA and zif268 mRNA were unaffected. The rapid inhibition of the stress-induced rise in POMC hnRNA in the anterior pituitary appears to reflect direct, GR-mediated suppression of POMC gene expression. RU28362 pretreatment 180 min before restraint onset was sufficient to suppress the stress-induced expression in the anterior pituitary gland of all three genes examined. Thus, the delayed negative feedback effects on hypothalamic-pituitary-adrenal axis activity that emerged after 180 min after glucocorticoid treatment were not evident at 60 min. Taken together, the data suggest that the inhibition of the stress-induced release of ACTH apparent within the first hour of glucocorticoid exposure is effected at the level of the pituitary gland. The delayed glucocorticoid effects evident 180 min after RU28362 treatment may include glucocorticoid actions in the brain and additional actions within the pituitary.

Ovulation detection methods for urinary hormones: precision, daily and intermittent sampling and a combined hierarchical method.

BACKGROUND: We evaluate the performance of ovulation detection methods and present new approaches, including evaluation of methods for precision, combining multiple markers into a hierarchical system and using ovulation markers in intermittent sampling designs. METHODS: With serum LH peak day as the 'gold standard' of ovulation, we estimated accuracy and precision of ovulation day algorithms using 30 ovulatory menstrual cycles with daily urinary and serum hormones and transvaginal ultrasound. Sensitivity and specificity for estimating the presence of ovulation were tested using visually assessed ovulatory (30) and anovulatory (22) cycles. RESULTS: Sensitivity and specificity ranged from 70 to 100% for estimating presence of ovulation with twice-per-cycle, weekly, twice weekly, every-other-day and daily specimens. A combined hierarchical method estimated ovulation day using daily specimens within +/-2 days of the gold standard in 93% of cases. Accuracy of estimating ovulation day within +/-2 days using intermittent sampling ranged from 40% (weekly sampling) to 97% (every-other-day). CONCLUSIONS: A combined hierarchical algorithm using precise and accurate markers allows maximal use of available data for efficient and objective identification of ovulation using daily specimens. In intermittent sampling designs, the presence and the timing of ovulation can be estimated with good sensitivity, specificity and accuracy.

Evidence that exogenous and endogenous fractalkine can induce spinal nociceptive facilitation in rats.

Recent evidence suggests that spinal cord glia can contribute to enhanced nociceptive responses. However, the signals that cause glial activation are unknown. Fractalkine (CX3C ligand-1; CX3CL1) is a unique chemokine expressed on the extracellular surface of spinal neurons and spinal sensory afferents. In the dorsal spinal cord, fractalkine receptors are primarily expressed by microglia. As fractalkine can be released from neurons upon strong activation, it has previously been suggested to be a neuron-to-glial signal that induces glial activation. The present series of experiments provide an initial investigation of the spinal pain modulatory effects of fractalkine. Intrathecal fractalkine produced dose-dependent mechanical allodynia and thermal hyperalgesia. In addition, a single injection of fractalkine receptor antagonist (neutralizing antibody against rat CX3C receptor-1; CX3CR1) delayed the development of mechanical allodynia and/or thermal hyperalgesia in two neuropathic pain models: chronic constriction injury (CCI) and sciatic inflammatory neuropathy. Intriguingly, anti-CX3CR1 reduced nociceptive responses when administered 5-7 days after CCI, suggesting that prolonged release of fractalkine may contribute to the maintenance of neuropathic pain. Taken together, these initial investigations of spinal fractalkine effects suggest that exogenous and endogenous fractalkine are involved in spinal sensitization, including that induced by peripheral neuropathy.

The role of IL-1beta in stress-induced sensitization of proinflammatory cytokine and corticosterone responses.

Proinflammatory cytokines often sensitize neuronal, hormonal, and behavioral responses to subsequent challenge. Recently, it was observed that exposure to inescapable tailshock enhances peripheral and central proinflammatory cytokine and corticosterone (CORT) responses to subsequent immune challenge up to 4 days later. Thus, we examined the role of central interleukin-1beta (IL-1beta) in stress-induced sensitization of proinflammatory cytokine and CORT responses to a subsequent immune challenge. Rats were administered IL-1 receptor antagonist (IL-1ra) or vehicle into the intra-cisterna magna 1 h prior to tailshock (100, 1.6 mA 5 s shocks) exposure. Twenty-four hours later, rats were challenged i.p. with 10 microg/kg lipopolysaccharide (LPS) and killed 1 h later. IL-1ra had no effect on basal proinflammatory cytokines, but completely blocked the stress-induced enhancement in central and pituitary IL-1beta and plasma IL-6 release following LPS challenge. IL-1ra had no effect on stress-induced enhancement in CORT responses following LPS challenge. Additional rats were administered i.c.v. hrIL-1beta or vehicle and returned to their home cage. Twenty-four hours later, rats were challenged i.p. with either saline or 10 microg/kg LPS and killed 1 h later. Central hrIL-1beta administration significantly elevated central IL-1beta levels and plasma CORT following LPS challenge compared with vehicle-injected controls. These data demonstrate that elevations in central IL-1beta, whether stress-induced or exogenously administered, are sufficient for sensitizing central IL-1beta and CORT responses to subsequent immune challenge. However, during times of stress, exogenous central IL-1ra administration only blocked sensitization of subsequent central IL-1beta responses, not CORT responses, suggesting other factors during the stress response can sensitize CORT responses.

Antibiotic prescribing policy and Clostridium difficile diarrhoea.

BACKGROUND: Broad-spectrum antibiotics, particularly intravenous cephalosporins, are associated with Clostridium difficile diarrhoea. Diarrhoea due to C. difficile is a growing problem in hospitals, especially among elderly patients. AIM: To establish whether changing an antibiotic policy with the aim of reducing the use of injectable cephalosporins leads to a reduction in the incidence of C. difficile diarrhoea in elderly patients. DESIGN: Retrospective analysis. METHODS: A group of patients who were subject to the new antibiotic policy from the period following July 2000, were compared with patients who were admitted prior to July 2000 and were not subject to the new policy. Infections, antibiotic prescriptions and mortality rates were determined from case notes, and C. difficle diarrhoea rates from microbiological data. RESULTS: Intravenous cephalosporin use fell from 210 to 28 defined daily doses (p < 0.001) following the change in antibiotic policy, with a corresponding increase in piperacillin-tazobactam (p < 0.001) and moxifloxacin (p < 0.001) use. The new policy led to a significant reduction in C. difficile diarrhoea cases. The relative risk of developing C. difficile infection with the old policy compared to the new policy was 3.24 (95%CI 1.07-9.84, p = 0.03). DISCUSSION: The antibiotic policy was successfully introduced into an elderly care service. It reduced both intravenous cephalosporin use and C. difficile diarrhoea.

Circulating cytokines and endotoxin are not necessary for the activation of the sickness or corticosterone response produced by peripheral E. coli challenge.

Peripheral administration of a variety of inflammatory stimuli, such as endotoxin or cytokines, induces an orchestrated set of brain-mediated events referred to as the sickness response. The mechanism for how immune products signal the brain is not clear, but accumulating evidence supports the existence of neural as well as blood-borne pathways. Although endotoxin or cytokine administration results in sickness responses, few data exist regarding the role of circulating endotoxin or cytokines in the induction of sickness during a real bacterial infection. Thus the present studies examined whether subcutaneously administered Escherichia coli can activate sickness responses and whether circulating endotoxin and/or proinflammatory cytokines are a prerequisite for these responses. Male Sprague-Dawley rats were injected subcutaneously with one of three doses (2.5 x 10(7), 2.5 x 10(8), 2.5 x 10(9) colony-forming units) of replicating E. coli, a ubiquitous bacterial strain, or vehicle. Core body temperature (Tc) and activity were measured for 3 days after the injection. A second set of groups of animals were killed 3, 6, 12, 18, 24, and 48 h after the injection, and blood samples and brains were collected. Injections dose dependently and consistently increased Tc and decreased activity, with increases in Tc beginning 4 h after the injection. In addition, E. coli significantly increased serum interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha and brain IL-1beta levels beginning at the 6-h time point. Corticosterone and endotoxin were first elevated in the circulation at 3 and 18 h after the injection, respectively. Because fever onset preceded brain cytokine induction, we also examined cytokine levels in the serum, brain, and inflammation site 2 and 4 h after injection. Cytokines were elevated at the inflammation site but were not detectable in the serum or brain at 2 and 4 h. We conclude that subcutaneous injection of replicating E. coli induces a consistent and naturalistic infection that includes features of the sickness response as well as increases in circulating, brain, and inflammation site tissue cytokines. In addition, injection of replicating E. coli produces a robust fever and corticosterone response at a time when there are no detectable increases in circulating cytokines or endotoxin. These results suggest that elevated levels of circulating cytokines and endotoxin are not necessary for the activation of the sickness or corticosterone response. Therefore, fever, activity reduction, and corticosterone elevation induced by E. coli infection may have been evoked by a neural, rather than a humoral, pathway from the periphery to the brain.

Inescapable shock induces resistance to the effects of dexamethasone.

Administration of bacterial endotoxin (lipopolysachharide; LPS) elevates proinflammatory cytokines, such as interleukin-1beta (IL-1beta) and IL-6, and activates the hypothalamic-pituitary-adrenal (HPA) axis. Corticosterone (CORT), the glucocorticoid (GC) effector hormone of the HPA axis in rats, inhibits both proinflammatory cytokine production/release and activity of the HPA axis itself. Exposure to chronic or repeated stressors often induces resistance to the effects of GCs. The following experiments were conducted to test the hypothesis that an acute stressor, inescapable tailshock (IS), alters responsivity of the HPA axis and proinflammatory cytokine system to dexamethasone (DEX), a synthetic GC. First, we examined the ability of various doses of DEX to suppress proinflammatory cytokine and HPA activity in response to LPS challenge 24 h after either home cage (HCC) or IS treatment. Upon finding resistance to DEX in IS animals, we examined the duration of the altered response to DEX by testing animals 1, 4 and 21 days after IS. To test whether IS animals were selectively resistant to the suppressive effects of DEX on the response to LPS, the ability of DEX to suppress HPA activity in response to a non-inflammatory stressor, exposure to an elevated "pedestal", was assessed. Again, DEX resistance was observed in IS animals. Finally, we examined whether changes in the responsivity to DEX were dependent upon the controllability of the stressor. The induction of DEX resistance was independent of the degree of behavioral control that the animal had over the stressor. Thus, a single session of IS induces DEX resistance of both HPA axis and cytokine responses measured in vivo.

Blockade of alpha1 adrenoreceptors in the dorsal raphe nucleus prevents enhanced conditioned fear and impaired escape performance following uncontrollable stressor exposure in rats.

Previous research has shown that the effect of exposure to uncontrollable stressors on conditioned fear responding and escape behavior in rats is dependent on serotonergic neural activity in the dorsal raphe nucleus (DRN). The role that norepinephrine released in the DRN plays in producing the behavioral consequences of exposure to inescapable tail shock in rats was investigated in the present study. The selective alpha1 adrenoreceptor antagonist benoxathian was injected into the DRN before exposure to inescapable tail shock or before behavioral testing conducted 24 h later. Benoxathian prevented the impairment of escape responding produced by inescapable shock, but did not reverse this effect when given before testing. The enhancement of conditioned fear produced by prior inescapable shock was attenuated by benoxathian administered before inescapable shock or before behavioral testing. These results support the view that noradrenergic input to the DRN is necessary to produce the behavioral effects of inescapable tail shock.

Menstrual cycle variability and the perimenopause.

Menopause, the final cessation of menstrual cycling, occurs when the pool of ovarian follicles is depleted. The one to five years just prior to the menopause are usually marked by increasing variability in menstrual cycle length, frequency of ovulation, and levels of reproductive hormones. Little is known about the mechanisms that account for these characteristics of ovarian cycles as the menopause approaches. Some evidence suggests that the dwindling pool of follicles itself is responsible for cycle characteristics during the perimenopausal transition. Another hypothesis is that the increased variability reflects "slippage" of the hypothalamus, which loses the ability to regulate menstrual cycles at older reproductive ages. This paper examines the underlying cause of the increasing variability in menstrual cycle length prior to the menopause. A model of ovarian cycles is developed, based on the process of follicular growth and depletion. Under this model, the follicular phase of each menstrual cycle is preceded by an inactive phase, a period of time when no ovarian follicles have left the resting state and begun secreting steroids in response to gonadotropin stimulation. The model makes predictions about the variability in menstrual cycles across the reproductive life span based on the size of the surviving pool of ovarian follicles. We show that the model can explain several characteristics of the perimenopause in humans and macaques and illustrate how the model can be applied to research on the biological and cultural correlates of the timing of menopause.

Intrathecal HIV-1 envelope glycoprotein gp120 induces enhanced pain states mediated by spinal cord proinflammatory cytokines.

Perispinal (intrathecal) injection of the human immunodeficiency virus-1 (HIV-1) envelope glycoprotein gp120 creates exaggerated pain states. Decreases in response thresholds to both heat stimuli (thermal hyperalgesia) and light tactile stimuli (mechanical allodynia) are rapidly induced after gp120 administration. gp120 is the portion of HIV-1 that binds to and activates microglia and astrocytes. These glial cells have been proposed to be key mediators of gp120-induced hyperalgesia and allodynia because these pain changes are blocked by drugs thought to affect glial function preferentially. The aim of the present series of studies was to determine whether gp120-induced pain changes involve proinflammatory cytokines [interleukin-1beta (IL-1) and tumor necrosis factor-alpha (TNF-alpha)], substances released from activated glia. IL-1 and TNF antagonists each prevented gp120-induced pain changes. Intrathecal gp120 produced time-dependent, site-specific increases in TNF and IL-1 protein release into lumbosacral CSF; parallel cytokine increases in lumbar dorsal spinal cord were also observed. Intrathecal administration of fluorocitrate (a glial metabolic inhibitor), TNF antagonist, and IL-1 antagonist each blocked gp120-induced increases in spinal IL-1 protein. These results support the concept that activated glia in dorsal spinal cord can create exaggerated pain states via the release of proinflammatory cytokines.

The contribution of the vagus nerve in interleukin-1beta-induced fever is dependent on dose.

It has been suggested that proinflammatory cytokines communicate to the brain via a neural pathway involving activation of vagal afferents by interleukin-1beta (IL-1beta), in addition to blood-borne routes. In support, subdiaphragmatic vagotomy blocks IL-1beta-induced, brain-mediated responses such as fever. However, vagotomy has also been reported to be ineffective. Neural signaling would be expected to be especially important at low doses of cytokine, when local actions could occur, but only very small quantities of cytokine would become systemic. Here, we examined core body temperature after intraperitoneal injections of three doses of recombinat human IL-1beta (rh-IL-1beta). Subdiaphragmatic vagotomy completely blocked the fever produced by 0.1 microg/kg, only partially blocked the fever produced by 0.5 microg/kg, and had no effect at all on the fever that followed 1.0 microg/kg rh-IL-1beta. Blood levels of rh-IL-1beta did not become greater than normal basal levels of endogenous rat IL-beta until the 0.5-microg/kg dose nor was IL-1beta induced in the pituitary until this dose. These results suggest that low doses of intraperitoneal IL-1beta induce fever via a vagal route and that dose may account for some of the discrepancies in the literature.

Systemic administration of CNI-1493, a p38 mitogen-activated protein kinase inhibitor, blocks intrathecal human immunodeficiency virus-1 gp120-induced enhanced pain states in rats.

Intrathecal administration of the human immunodeficiency virus-1 envelope glycoprotein, gp120, activates astrocytes and microglia to release products that induce thermal hyperalgesia and mechanical allodynia. Both pain states are disrupted by intrathecal CNI-1493, a p38 mitogen-activated protein (MAP) kinase inhibitor. Whether CNI-1493, or any other p38 MAP kinase inhibitor, can cross the blood-brain barrier to affect spinal cord function is unknown. Given that several such drugs are in clinical trials, it is of interest to determine whether they may be potentially useful in treating centrally mediated pain. The aim of the present studies was to determine whether systemic CNI-1493 could block intrathecal gp120-induced thermal hyperalgesia and/or mechanical allodynia. Because p38 MAP kinase inhibition would be expected to prevent proinflammatory cytokine release and/or signal transduction, we sought to determine from the same animals the likely mechanism by which CNI-1493 blocks gp120-induced pain states. These studies show that systemic CNI-1493 blocks intrathecal gp120-induced thermal hyperalgesia and mechanical allodynia. Because CNI-1493 did not block proinflammatory cytokine release, this may suggest disruption at the level of signal transduction. These studies provide the first evidence that systemic p38 MAP kinase inhibitors can prevent centrally mediated exaggerated pain states. Thus, CNI-1493 may provide a novel therapeutic approach for the treatment of pain.

Sciatic inflammatory neuritis (SIN): behavioral allodynia is paralleled by peri-sciatic proinflammatory cytokine and superoxide production.

We have recently developed a model of sciatic inflammatory neuritis (SIN) to assess how immune activation near peripheral nerves influences somatosensory processing. Administration of zymosan (yeast cell walls) around a single sciatic nerve produces dose-dependent low-threshold mechanical allodynia without thermal hyperalgesia. Low (4 microg) doses produce both territorial and extraterritorial allodynia restricted to the injected hindleg. In contrast, higher (40 microg) doses produce territorial and extraterritorial allodynias of both hindlegs, an effect not accounted for by systemic spread of the zymosan. The aim of these experiments was to determine whether these behavioral allodynias were correlated with immunological and/or anatomical changes in or around the sciatic nerve. These experiments reveal that zymosan-induced bilateral allodynia was associated with the following: (a) increased release of both interleukin-1beta and tumor necrosis factor-alpha from peri-sciatic immune cells; (b) increased release of reactive oxygen species from perisciatic immune cells; (c) no change in circulating levels of proinflammatory cytokine; (d) no apparent zymosan-induced influx of immune cells into the sciatic nerve from the endoneurial blood vessels; (e) mild edema of the sciatic, which was predominantly restricted to superficial regions closest to the peri-sciatic immune cells; and (f) no anatomic evidence of changes in either the ipsilateral saphenous nerve or contralateral sciatic nerve that could account for the appearance of extraterritorial or contralateral ("mirror") allodynia, respectively. No reliable differences were found when the low-dose zymosan was compared with vehicle controls. Taken together, these data suggest that substances released by peri-sciatic immune cells may induce changes in the sciatic nerve, leading to the appearance of bilateral allodynia.

Developmental aggregation of Myxococcus xanthus requires frgA, an frz-related gene.

Myxococcus xanthus is a gram-negative bacterium which has a complex life cycle that includes multicellular fruiting body formation. Frizzy mutants are characterized by the formation of tangled filaments instead of hemispherical fruiting bodies on fruiting agar. Mutations in the frz genes have been shown to cause defects in directed motility, which is essential for both vegetative swarming and fruiting body formation. In this paper, we report the discovery of a new gene, called frgA (for frz-related gene), which confers a subset of the frizzy phenotype when mutated. The frgA null mutant showed reduced swarming and the formation of frizzy aggregates on fruiting agar. However, this mutant still displayed directed motility in a spatial chemotaxis assay, whereas the majority of frz mutants fail to show directed movements in this assay. Furthermore, the frizzy phenotype of the frgA mutant could be complemented extracellularly by wild-type cells or strains carrying non-frz mutations. The phenotype of the frgA mutant is similar to that of the abcA mutant and suggests that both of these mutants could be defective in the production or export of extracellular signals required for fruiting body formation rather than in the sensing of such extracellular signals. The frgA gene encodes a large protein of 883 amino acids which lacks homologues in the databases. The frgA gene is part of an operon which includes two additional genes, frgB and frgC. The frgB gene encodes a putative histidine protein kinase, and the frgC gene encodes a putative response regulator. The frgB and frgC null mutants, however, formed wild-type fruiting bodies.