The p53-mdm-2 autoregulatory feedback loop

The p53 protein can bind to a set of specific DNA sequences, and this may activate the transcription of genes adjacent to these DNA elements. The mdm-2 gene is shown here to contain a p53 DNA-binding site and a genetically responsive element such that expression of the mdm-2 gene can be regulated by the level of wild-type p53 protein. The mdm-2 protein, in turn, can complex with p53 and decrease its ability to act as a positive transcription factor at the mdm-2 gene-responsive element. In this way, the mdm-2 gene is autoregulated. The p53 protein regulates the mdm-2 gene at the level of transcription, and the mdm-2 protein regulates the p53 protein at the level of its activity. This creates a feedback loop that regulates both the activity of the p53 protein and the expression of the mdm-2 gene.

Expression of relB is required for the development of thymic medulla and dendritic cells

Dendritic cells (DC) derived from bone marrow are critical in the function of the immune system, for they are the primary antigen-presenting cells in the activation of T-lymphocyte response. Their differentiation from precursor cells has not been defined at a molecular level, but recent studies have shown an association between expression of the relB subunit of the NF-kappa B complex and the presence of DC in specific regions of normal unstimulated lymphoid tissues. Here we show that relB expression also correlates with differentiation of DC in autoimmune infiltrates in situ, and that a mutation disrupting the relB gene results in mice with impaired antigen-presenting cell function, and a syndrome of excess production of granulocytes and macrophages. Thymic UEA-1+ medullary epithelial cells from normal mice show striking similarities to DC and, interestingly, these cells are also absent in relB mutant mice. Taken together, these results suggest that relB is critical in the coordinated activation of genes necessary for the differentiation of two unrelated but phenotypically similar cells (DC and thymic UEA-1+ medullary epithelial cells) and is therefore a candidate for a gene determining lineage commitment in the immune system.

Conditional vascular cell adhesion molecule 1 deletion in mice: impaired lymphocyte migration to bone marrow

We generated vascular cell adhesion molecule (VCAM)-1 "knock-in" mice and Cre recombinase transgenic mice to delete the VCAM-1 gene (vcam-1) in whole mice, thereby overcoming the embryonic lethality seen with conventional vcam-1-deficient mice. vcam-1 knock-in mice expressed normal levels of VCAM-1 but showed loss of VCAM-1 on endothelial and hematopoietic cells when interbred with a "TIE2Cre" transgene. Analysis of peripheral blood from conditional vcam-1-deficient mice revealed mild leukocytosis, including elevated immature B cell numbers. Conversely, the bone marrow (BM) had reduced immature B cell numbers, but normal numbers of pro-B cells. vcam-1-deficient mice also had reduced mature IgD+ B and T cells in BM and a greatly reduced capacity to support short-term migration of transferred B cells, CD4+ T cells, CD8+ T cells, and preactivated CD4+ T cells to the BM. Thus, we report an until now unappreciated dominant role for VCAM-1 in lymphocyte homing to BM.

Recycling of the urokinase receptor upon internalization of the uPA:serpin complexes

The GPI-anchored urokinase plasminogen activator receptor (uPAR) does not internalize free urokinase (uPA) but readily internalizes and degrades uPA:serpin complexes in a process that requires the alpha2-macroglobulin receptor/low density lipoprotein receptor-related protein (alpha2MR-LRP). This process is accompanied by the internalization of uPAR which renders it resistant to phosphatidylinositol-specific phospholipase C (PI-PLC). In this paper we show that during internalization of uPA:serpins at 37 degrees C, analysed by FACScan, immunofluorescence and immunoelectron microscopy, an initial decrease of cell surface uPAR was observed, followed by its reappearance at later times. This effect was not due to redistribution of previously intracellular receptors, nor to the surface expression of newly synthesized uPAR. Recycling was directly demonstrated in cell surface-biotinylated, uPA:PAI-1-exposed cells in which biotinylated uPAR was first internalized and subsequently recycled back to the surface upon incubation at 37 degrees C. In fact, uPAR was resistant to PI-PLC after the 4 degrees C binding of uPA:PAI-1 to biotinylated cells, but upon incubation at 37 degrees C PI-PLC-sensitive biotinylated uPAR reappeared at the cell surface. Binding of uPA:PAI-1 by uPAR, while essential to initiate the whole process, was, however, dispensable at later stages as both internalization and recycling of uPAR could be observed also after dissociation of the bound ligand from the cell surface.

Model curriculum for physician training in emergency ultrasonography

A model curriculum for the implementation and training of physicians in emergency medicine ultrasonography is described. Widespread use of limited bedside ultrasonography by emergency physicians will improve diagnostic accuracy and efficiency, increase the quality of care, and prove to be a cost-effective technique for the practice of emergency medicine.

Effects of decreased respiratory frequency on ventilator-induced lung injury

To determine if decreased respiratory frequency (ventilatory rate) improves indices of lung damage, 17 sets of isolated, perfused rabbit lungs were ventilated with a peak static airway pressure of 30 cm H(2)O. All lungs were randomized to one of three frequency/peak pulmonary artery pressure combinations: F20P35 (n = 6): ventilatory frequency, 20 breaths/min, and peak pulmonary artery pressure, 35 mm Hg; F3P35 (n = 6), ventilatory frequency, 3 breaths/min, and peak pulmonary artery pressure of 35 mm Hg; or F20P20 (n = 5), ventilatory frequency, 20 breaths/min, and peak pulmonary artery pressure, 20 mm Hg. Mean airway pressure and tidal volume were matched between groups. Mean pulmonary artery pressure and vascular flow were matched between groups F20P35 and F3P35. The F20P35 group showed at least a 4.5-fold greater mean weight gain and a 3-fold greater mean incidence of perivascular hemorrhage than did the comparison groups, all p </= 0.05. F20P35 lungs also displayed more alveolar hemorrhage than did F20P20 lungs (p </= 0.05). We conclude that decreasing respiratory frequency can improve these indices of lung damage, and that limitation of peak pulmonary artery pressure and flow may diminish lung damage for a given ventilatory pattern.

Effect of cooling on oxygen consumption in febrile critically ill patients

Hyperthermic critically ill patients are commonly cooled to reduce their oxygen consumption (VO2). However, no previous studies in febrile humans have measured VO2 during cooling. We cooled 12 febrile, critically ill, mechanically ventilated patients while measuring VO2 and CO2 production (VCO2) by analysis of inspired and expired gases. All patients were mechanically ventilated for hypoxemic, hypercapneic, or shock-related respiratory failure and had a mean APACHE II score of 22.4 +/- 7.7. As temperature was reduced from 39.4 +/- 0.8 to 37.0 +/- 0.5 degrees C, VO2 decreased from 359.0 +/- 65.0 to 295.1 +/- 57.3 ml/min (p < 0.01) and VCO2 decreased from 303.6 +/- 43.6 to 243.5 +/- 37.3 ml/min (p < 0.01). The respiratory quotient (RQ) did not change significantly, and calculated energy expenditure decreased from 2,481 +/- 426 to 1,990 +/- 33 kcal/day (p < 0.01). In 7 patients with right heart catheters, cardiac output decreased from 8.4 +/- 3.2 to 6.5 +/- 1.8 L/min (p < 0.01) as the oxygen extraction fraction also tended to decrease from a mean of 28.2 +/- 6.8 to 23.4 +/- 4.7% (p = 0.12) during cooling. Accordingly, cooling the febrile patient unloads the cardiorespiratory system and, in situations of limited oxygen delivery or hypoxemic respiratory failure, may thus facilitate resuscitation and minimize the potential for hypoxic tissue injury.

Sedation of critically ill patients during mechanical ventilation. A comparison of propofol and midazolam

Propofol (P) and midazolam (M) are frequently given by continuous infusion for sedation in critically ill, mechanically ventilated patients. We compared these drugs with regard to: (1) time-to-awaken; (2) reproducibility of bedside assessments of level of sedation; (3) time-to-sedation; and (4) change in oxygen consumption (V O2) from awake to sedated state. Seventy-three patients were prospectively randomized to receive either P (n=37) or M (n=36). Wake-up times after stopping the drug were assessed by blinded and unblinded observers, by asking patients to perform simple tasks. Times to sedate were assessed by consensus agreement among nurses and investigators. Demographics and APACHE II scores were not different between P and M. The P group had a significantly narrower range of wake-up times with a higher likelihood of waking in less than 60 min. Blinded versus unblinded observations had excellent correlation. Average time to sedate and decrease in V O2 were not different. We conclude that in this patient population: (1) both P and M achieved optimal sedation in a large fraction of patients when administered by specified dosing protocols; (2) P had a faster, more reliable, wake-up time; (3) assessments of time-to-awaken were objective and reproducible; (4) time to sedation was not significantly different; (5) V O2 decreased similarly with both.

From individuals to aggregations: the interplay between behavior and physics

This paper analyses the processes by which organisms form groups and how social forces interact with environmental variability and transport. For aquatic organisms, the latter is especially important-will sheared or turbulent flows disrupt organism groups? To analyse such problems, we use individual-based models to study the environmental and social forces leading to grouping. The models are then embedded in turbulent flow fields to gain an understanding of the interplay between the forces acting on the individuals and the transport induced by the fluid motion. Instead of disruption of groups, we find that flows often enhance grouping by increasing the encounter rate among groups and thereby promoting merger into larger groups; the effect breaks down for strong flows. We discuss the transformation of individual-based models into continuum models for the density of organisms. A number of subtle difficulties arise in this process; however, we find that a direct comparison between the individual model and the continuum model is quite favorable. Finally, we examine the dynamics of group statistics and give an example of building an equation for the spatial and temporal variations of the group-size distribution from the individual-based simulations. These studies lay the groundwork for incorporating the effects of grouping into models of the large scale distributions of organisms as well as for examining the evolutionary consequences of group formation.

Extracellular calcium elicits a chemokinetic response from monocytes in vitro and in vivo

Recruitment of macrophages to sites of cell death is critical for induction of an immunologic response. Calcium concentrations in extracellular fluids vary markedly, and are particularly high at sites of injury or infection. We hypothesized that extracellular calcium participates in modulating the immune response, perhaps acting via the seven-transmembrane calcium-sensing receptor (CaR) on mature monocytes/macrophages. We observed a dose-dependent increase in monocyte chemotaxis in response to extracellular calcium or the selective allosteric CaR activator NPS R-467. In contrast, monocytes derived from mice deficient in CaR lacked the normal chemotactic response to a calcium gradient. Notably, CaR activation of monocytes bearing the receptor synergistically augmented the transmigration response of monocytes to the chemokine MCP-1 in association with increased cell-surface expression of its cognate receptor, CCR2. Conversely, stimulation of monocytes with MCP-1 or SDF-1alpha reciprocally increased CaR expression, suggesting a dual-enhancing interaction of Ca(2+) with chemokines in recruiting inflammatory cells. Subcutaneous administration in mice of Ca(2+), MCP-1, or (more potently) the combination of Ca(2+) and MCP-1, elicited an inflammatory infiltrate consisting of monocytes/macrophages. Thus extracellular calcium functions as an ionic chemokinetic agent capable of modulating the innate immune response in vivo and in vitro by direct and indirect actions on monocytic cells. Calcium deposition may be both consequence and cause of chronic inflammatory changes at sites of injury, infection, and atherosclerosis.

Consequences of vascular flow on lung injury induced by mechanical ventilation

To investigate whether the magnitude of blood flow contributes to ventilator-induced lung injury, 14 sets of isolated rabbit lungs were randomized for perfusion at either 300 (Group A: n = 7) or 900 ml/ min (Group B: n = 7) while ventilated with 30 cm H2O peak static pressure. Control lungs (Group C: n = 7) were ventilated with lower peak static pressure (15 cm H2O) and perfused at 500 ml/min. Weight gain, changes in the ultrafiltration coefficient (DeltaKf) and lung static compliance (CL), and extent of hemorrhage (scored by histology) were compared. Group B had a larger decrease in CL (-13 +/- 11%) than Groups A (2 +/- 6%) and C (5 +/- 5%) (p < 0.05). Group B had more hemorrhage and gained more weight (16.2 +/- 9.5 g) than Groups A (8.7 +/- 3.4 g) and C (1.6 +/- 1.0 g) (p < 0.05 for each pairwise comparison between groups). Finally, Kf (g . min-1 . cm H2O-1 . 100 g-1) increased the most in Group B (DeltaKf = 0.26 +/- 0. 20 versus 0.17 +/- 0.10 in Group A and 0.05 +/- 0.04 in Group C; p < 0.05 for B versus C). We conclude that the intensity of lung perfusion contributes to ventilator- induced lung injury in this model.

The association of swallowing dysfunction and aspiration pneumonia

The medical literature has emphasized that aspiration of gastric contents or oral bacteria is a common cause of aspiration pneumonia. Swallowing disorders have been implicated in this disease but not studied at the time that aspiration pneumonia was diagnosed. A significant difference was found in the incidence of videofluoroscopically confirmed oropharyngeal swallowing problems in a group of patients diagnosed with aspiration pneumonia (AP) when compared with patients with nonaspiration pneumonia (NAP). Six of the 9 patients in the AP group aspirated during the videofluoroscopic evaluation and 2 others were considered to be at risk for aspiration. None of the 7 NAP patients demonstrated swallowing problems or aspiration. A significant difference in oral transit time also occurred between the two groups. Liquid was found to have a significantly faster oral transit time than paste or a cookie. Pharyngeal transit times were not found to be significantly different. Although there were only a small number of patients who met the criteria for this pilot study, a strong association was found between swallowing dysfunction and aspiration pneumonia.

Progressive supranuclear palsy: neuropathologic and clinical heterogeneity

To investigate potential heterogeneity in progressive supranuclear palsy (PSP), we examined 13 patients with neuropathologically diagnosed PSP. The clinical diagnosis of PSP was made in eight of these individuals, whereas probable AD was the primary diagnosis in the remaining five. In addition to PSP neuropathology, seven of the 13 patients (54%) showed concomitant pathologic changes of Alzheimer's disease (AD), Parkinson's disease (PD), or both disorders. These observations indicate that AD and PD changes coexist with PSP neuropathology in a substantive proportion of patients and provide further evidence of clinical and neuropathologic heterogeneity in neurodegenerative disorders. Moreover, our results suggest that PSP may be underdiagnosed and deserves more prominence in the differential diagnosis of dementing illness.

Diagnosis of hysterical seizures in epileptic patients

The coexistence of epileptic and hysterical seizures in the same patient is not rare and creates problems in diagnosis and management. The authors used simultaneous video-EEG monitoring to document the diagnosis of hysterical seizures in 9 epileptic patients; clear-cut hysterical seizures were seen in all 9. The authors used individualized re-educative psychotherapy to teach patients alternative coping techniques and discharged them on minimum dosages of anticonvulsants. None of the patients had a classical hysterical personality, which suggests that conversion reaction is a more appropriate diagnosis, The etiology of "hysterical" seizures varies; the authors emphasize individualized treatment and long-term follow-up.

Elliptic flow in Au+Au collisions at square root(S)NN = 130 GeV

Elliptic flow from nuclear collisions is a hadronic observable sensitive to the early stages of system evolution. We report first results on elliptic flow of charged particles at midrapidity in Au+Au collisions at square root(S)NN = 130 GeV using the STAR Time Projection Chamber at the Relativistic Heavy Ion Collider. The elliptic flow signal, v2, averaged over transverse momentum, reaches values of about 6% for relatively peripheral collisions and decreases for the more central collisions. This can be interpreted as the observation of a higher degree of thermalization than at lower collision energies. Pseudorapidity and transverse momentum dependence of elliptic flow are also presented.

Should the elderly be resuscitated following out-of-hospital cardiac arrest?

PURPOSE

Elderly and younger patients who were successfully resuscitated and hospitalized following out-of-hospital cardiac arrest were studied to determine if there was a significant difference in hospital course and long-term survival between the two groups.

PATIENTS AND METHODS

The study consisted of 214 consecutive patients, divided into two age groups: elderly (more than 70 years, n = 112) and younger (less than 70 years, n = 102). Hospital charts and paramedic run data were retrospectively reviewed for each patient and findings were compared between the two age groups.

RESULTS

Prior to cardiac arrest, 47 of 112 (42 percent) elderly patients had a history of heart failure, compared with 19 of 102 (18 percent) younger patients, and were more commonly taking digitalis (51 percent versus 29 percent) and diuretics (47 percent versus 26 percent). Younger patients, however, more often had an acute myocardial infarction at the time of the cardiac arrest (33 percent versus 16 percent). At the time of cardiac arrest, 83 percent of younger patients demonstrated ventricular fibrillation, compared with 71 percent of the elderly. In contrast, electromechanical dissociation was five times more common in the elderly patients. Although hospital deaths were more common in the elderly (71 percent versus 53 percent), the length of hospitalization and stay in intensive care units were not significantly different between the age groups. The number of neurologic deaths was similar in both age groups, as were residual neurologic impairments. Only five elderly patients and six younger patients required placement in extended-care facilities. Calculated long-term survival curves demonstrated similar survival in both age groups, with approximately 65 percent of hospital survivors alive at 24 months after hospital discharge.

CONCLUSION

Resuscitation of elderly patients in whom out-of-hospital cardiac arrest occurs is reasonable and appropriate, according to the findings of this study. Even though elderly patients are more likely than younger patients to die during hospitalization, the hospital stay of the elderly is not longer, the elderly do not have more residual neurologic impairments, and survival after hospital discharge is similar to that in younger patients.

Xenobiotic metabolism enzyme gene expression in human bronchial epithelial and alveolar macrophage cells

Human bronchial epithelial cells (BEC), a primary defense against inhaled materials, are the progenitor cells for bronchogenic carcinomas and have important metabolic capabilities. We used reverse transcriptase-polymerase chain reaction (RT-PCR) to identify xenobiotic metabolism enzymes expressed in primary BEC and alveolar macrophages (AM) of non-smoking volunteers. Cytochromes P450 (CYP) 1A1, 1B1, 2B7, 2E1, and 4B1 and microsomal epoxide hydrolase (mEH) were expressed in BEC but not AM. CYP2F1 was expressed in BEC, but it was expressed at barely detectable levels or not at all in AM. NADPH oxidoreductase (NADPH OR), microsomal glutathione transferase (GST 12), glutathione transferase mu, phenol sulfotransferase (PST), thermolabile phenol sulfotransferase (TL PST), and the clara cell-specific gene, CC10 were expressed in both BEC and AM. CYP3A4 and glucuronosyl transferases-1 and 2 were not expressed in either BEC or AM. In contrast to primary BEC, of the genes evaluated, the immortalized human bronchial epithelial cell line BEP2D constitutively expressed only CYP1A1, CYP2E1, NADPH OR, glucuronosyl transferase 1, GST 12, GST mu, PST, TL PST, and CC10. The loss of xenobiotic metabolism enzyme gene expression in the BEP2D cell line may result from either reduced exposure to inducing agents, or loss of differentiative characteristics in culture. It is clear from the data comparing BEC and AM that there are important intertissue differences in expression of xenobiotic metabolism enzymes.

Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies

We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5<p(T)<12 GeV/c. The collision energy dependence of the yields and the centrality and p(T) dependence of the suppression provide stringent constraints on theoretical models of suppression. Models incorporating initial-state gluon saturation or partonic energy loss in dense matter are largely consistent with observations. We observe no evidence of p(T)-dependent suppression, which may be expected from models incorporating jet attenuation in cold nuclear matter or scattering of fragmentation hadrons.

A "Global Safety Net" to reverse biodiversity loss and stabilize Earth's climate

Global strategies to halt the dual crises of biodiversity loss and climate change are often formulated separately, even though they are interdependent and risk failure if pursued in isolation. The Global Safety Net maps how expanded nature conservation addresses both overarching threats. We identify 50% of the terrestrial realm that, if conserved, would reverse further biodiversity loss, prevent CO₂ emissions from land conversion, and enhance natural carbon removal. This framework shows that, beyond the 15.1% land area currently protected, 35.3% of land area is needed to conserve additional sites of particular importance for biodiversity and stabilize the climate. Fifty ecoregions and 20 countries contribute disproportionately to proposed targets. Indigenous lands overlap extensively with the Global Safety Net. Conserving the Global Safety Net could support public health by reducing the potential for zoonotic diseases like COVID-19 from emerging in the future.

Production of the Mycotoxin Fumonisin B 1 by Alternaria alternata f. sp. lycopersici

The mycotoxin fumonisin B 1 , originally described as being produced by Fusarium moniliforme , was detected in liquid cultures of Alternaria alternata f. sp. lycopersici , a host-specific pathogen of tomato plants. The metabolite was detected by high-pressure liquid chromatography and mass spectrometry. Its identity was confirmed by fast atom bombardment and ion spray mass spectrometry, as well as parent-daughter tandem mass spectrometry. In three separate experiments, the concentrations found ranged between 5 and 140 ppm (μg/ml).

Azimuthal charged-particle correlations and possible local strong parity violation

Parity-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the system's orbital momentum axis. We investigate a three-particle azimuthal correlator which is a P even observable, but directly sensitive to the charge separation effect. We report measurements of charged hadrons near center-of-mass rapidity with this observable in Au + Au and Cu + Cu collisions at square root of s(NN) = 200 GeV using the STAR detector. A signal consistent with several expectations from the theory is detected. We discuss possible contributions from other effects that are not related to parity violation.

Centrality dependence of high-p(T) hadron suppression in Au+Au collisions at sqrt[s(NN)]=130 GeV

Inclusive transverse momentum distributions of charged hadrons within 0.2<p(T)<6.0 GeV/c have been measured over a broad range of centrality for Au+Au collisions at sqrt[s(NN)]=130 GeV. Hadron yields are suppressed at high p(T) in central collisions relative to peripheral collisions and to a nucleon-nucleon reference scaled for collision geometry. Peripheral collisions are not suppressed relative to the nucleon-nucleon reference. The suppression varies continuously at intermediate centralities. The results indicate significant nuclear medium effects on high-p(T) hadron production in heavy-ion collisions at high energy.

Initial evidence of endothelial cell apoptosis as a mechanism of systemic capillary leak syndrome

BACKGROUND

Systemic capillary leak syndrome (SCLS) is a rare disorder of unknown etiology that is characterized by acute recurrent attacks of hypovolemic shock commonly following an inflammatory stimulus such as a viral illness. Prophylactic therapy is generally ineffective, and the outcome is frequently fatal.

METHODS

In order to investigate the cellular mechanisms leading to SCLS, we examined the effects of sera from two patients with active SCLS on microvascular endothelial cell apoptosis in vitro. Apoptosis was determined by morphologic criteria, DNA fragmentation, annexin V stain, and by a quantitative photometric assay. The apoptotic pathway was investigated by Western blot of endothelial cells lysate after exposure to SCLS sera.

RESULTS

The sera from patients with active SCLS mediated profound apoptosis of microvascular endothelial cells shortly after exposure. The exposed microvascular endothelial cells underwent immediate apoptosis as evidenced by morphologic changes, plasma membrane phosphatidylserine exposure, and by DNA fragmentation. Increased Bax/Bcl-2 ratio in endothelial cells exposed to SCLS sera was observed and suggested an oxidation injury as the possible mechanism for endothelial apoptosis. This potential mechanism was further explored by measuring intracellular reactive oxygen species (ROS) following SCLS serum exposure. Sera from both patients caused marked increases in ROS, initially detectable at 1 h and persisted for at least 12 h, with control serum from healthy subjects showing no effect on basal endothelial cell ROS concentrations.

CONCLUSION

Components from the sera of patients with active systemic capillary leak syndrome in contrast to healthy subject sera mediate early and extensive endothelial apoptosis in vitro that is associated with oxidation injury. These data represent compelling initial evidence for oxidation-induced apoptosis as a likely mechanism for endothelial injury leading to SCLS.