Different learning aberrations relate to delusion-like beliefs with different contents

The prediction error account of delusions has had success. However, its explanation of delusions with different contents has been lacking. Persecutory delusions and paranoia are the common unfounded beliefs that others have harmful intentions towards us. Other delusions include believing that one's thoughts or actions are under external control, or that events in the world have specific personal meaning. We compare learning on two different cognitive tasks, probabilistic reversal learning (PRL) and Kamin blocking, that have relationships to paranoid and non-paranoid delusion-like beliefs, respectively. We find that Clinical High-Risk status alone does not result in different behavioral results on the PRL task but that an individual's level of paranoia is associated with excessive switching behavior. During the Kamin blocking task, paranoid individuals learned inappropriately about the blocked cue. However, they also had decreased learning about the control cue, suggesting more general learning impairments. Non-paranoid delusion-like belief conviction (but not paranoia) was associated with aberrant learning about the blocked cue but intact learning about the control cue, suggesting specific impairments in learning related to cue combination. We fit task-specific computational models separately to behavioral data to explore how latent parameters vary within individuals between tasks, and how they can explain symptom-specific effects. We find that paranoia is associated with low learning rates on the PRL task as well as the blocking task. Non-paranoid delusion-like belief conviction was instead related to parameters controlling the degree and direction of similarity between cue updating during simultaneous cue presentation. These results suggest that paranoia and other delusion-like beliefs involve dissociable deficits in learning and belief updating, which - given the transdiagnostic status of paranoia - may have differential utility in predicting psychosis.

Single-Cell Transcriptomic Analysis of Salivary Gland Endothelial Cells

Vascular endothelial cells have important tissue-specific functions in fibrosis and regeneration. In the salivary gland, endothelial cells are required for proper development, but their roles within adult glands are largely unknown. To identify ligand-receptor interactions between endothelial cells and other cell types that may be important during fibrosis and regeneration, we used a reversible ductal ligation injury. To induce injury, a clip was applied to the primary ducts for 14 d, and to induce a regenerative response, the clip was subsequently removed for 5 d. To identify endothelial cell-produced factors, we used single-cell RNA sequencing of stromal-enriched cells from adult female submandibular and sublingual salivary glands. Transcriptional profiles of homeostatic salivary gland endothelial cells were compared to endothelial cells of other organs. Salivary gland endothelial cells expressed many unique genes and displayed the highest overlap in gene expression with other fenestrated endothelial cells from the colon, small intestine, and kidney. Comparison of the 14-d ligated, mock-ligated, and 5-d deligated stromal-enriched transcripts and lineage tracing revealed that endothelial cells retain their identity following ligation and recovery from injury. CellChat and NATMI were used to predict changes in ligand-receptor interactions from endothelial cells to other cells in response to ligation and deligation. CellChat and NATMI predicted that after ligation, interactions with fibroblasts, epithelial cells, and glial cells were increased, and following deligation, interactions with pericyte, glia, fibroblasts, and immune cells were increased. Some of the highest-ranked interactions predicted in ligated compared to mock endothelial cells were between glial cells via Col4a2-Cd93 and Jag2-Notch1, as well as epithelial cells via Pecam1-Cd38, while in deligated compared to ligated endothelial cells, the top interactions were between fibroblasts via Ntf3-Ntrk2, glial cells via Hspg2-Itgb1, and pericytes via Jam2-F11r. Understanding salivary gland endothelial cell signaling will inform future endothelial cell-based regenerative therapies.

Relating Glutamate, Conditioned, and Clinical Hallucinations via 1H-MR Spectroscopy

BACKGROUND AND HYPOTHESIS

Hallucinations may be driven by an excessive influence of prior expectations on current experience. Initial work has supported that contention and implicated the anterior insula in the weighting of prior beliefs.

STUDY DESIGN

Here we induce hallucinated tones by associating tones with the presentation of a visual cue. We find that people with schizophrenia who hear voices are more prone to the effect and using computational modeling we show they overweight their prior beliefs. In the same participants, we also measured glutamate levels in anterior insula, anterior cingulate, dorsolateral prefrontal, and auditory cortices, using magnetic resonance spectroscopy.

STUDY RESULTS

We found a negative relationship between prior-overweighting and glutamate levels in the insula that was not present for any of the other voxels or parameters.

CONCLUSIONS

Through computational psychiatry, we bridge a pathophysiological theory of psychosis (glutamate hypofunction) with a cognitive model of hallucinations (prior-overweighting) with implications for the development of new treatments for hallucinations.

Computerized Assessment of Psychosis Risk

Early detection and intervention with young people at clinical high risk (CHR) for psychosis is critical for prevention efforts focused on altering the trajectory of psychosis. Early CHR research largely focused on validating clinical interviews for detecting at-risk individuals; however, this approach has limitations related to: (1) specificity (i.e., only 20% of CHR individuals convert to psychosis) and (2) the expertise and training needed to administer these interviews is limited. The purpose of our study is to develop the computerized assessment of psychosis risk (CAPR) battery, consisting of behavioral tasks that require minimal training to administer, can be administered online, and are tied to the neurobiological systems and computational mechanisms implicated in psychosis. The aims of our study are as follows: (1A) to develop a psychosis-risk calculator through the application of machine learning (ML) methods to the measures from the CAPR battery, (1B) evaluate group differences on the risk calculator score and test the hypothesis that the risk calculator score of the CHR group will differ from help-seeking and healthy controls, (1C) evaluate how baseline CAPR battery performance relates to symptomatic outcome two years later (i.e., conversion and symptomatic worsening). These aims will be explored in 500 CHR participants, 500 help-seeking individuals, and 500 healthy controls across the study sites. This project will provide a next-generation CHR battery, tied to illness mechanisms and powered by cutting-edge computational methods that can be used to facilitate the earliest possible detection of psychosis risk.

Increased face detection responses on the mooney faces test in people at clinical high risk for psychosis

Identifying state-sensitive measures of perceptual and cognitive processes implicated in psychosis may allow for objective, earlier, and better monitoring of changes in mental status that are predictive of an impending psychotic episode, relative to traditional self-report-based clinical measures. To determine whether a measure of visual perception that has demonstrated sensitivity to the clinical state of schizophrenia in multiple prior studies is sensitive to features of the at-risk mental state, we examined differences between young people identified as being at clinical high risk for psychosis (CHR; n = 37) and non-psychiatric matched controls (n = 29) on the Mooney Faces Test (MFT). On each trial of the MFT, participants report whether they perceive a face in a degraded face image. The CHR group reported perceiving a greater number of faces in both upright and inverted MFT stimuli. Consistent with prior work, males reported more faces on the MFT than females in both conditions. However, the finding of greater reported face perception among CHR subjects was robustly observed in the female CHR group relative to the female control group. Among male CHR participants, greater reported face perception was related to increased perceptual abnormalities. These preliminary results are consistent with a small but growing literature suggesting that heightened perceptual sensitivity may characterize individuals at increased clinical risk for psychosis. Further studies are needed to determine the contributions of specific perceptual, cognitive, and motivational mechanisms to the findings.

Paranoia and belief updating during a crisis

The 2019 coronavirus (COVID-19) pandemic has made the world seem unpredictable. During such crises we can experience concerns that others might be against us, culminating perhaps in paranoid conspiracy theories. Here, we investigate paranoia and belief updating in an online sample (N=1,010) in the United States of America (U.S.A). We demonstrate the pandemic increased individuals’ self-rated paranoia and rendered their task-based belief updating more erratic. Local lockdown and reopening policies, as well as culture more broadly, markedly influenced participants’ belief-updating: an early and sustained lockdown rendered people’s belief updating less capricious. Masks are clearly an effective public health measure against COVID-19. However, state-mandated mask wearing increased paranoia and induced more erratic behaviour. Remarkably, this was most evident in those states where adherence to mask wearing rules was poor but where rule following is typically more common. This paranoia may explain the lack of compliance with this simple and effective countermeasure. Computational analyses of participant behaviour suggested that people with higher paranoia expected the task to be more unstable, but at the same time predicted more rewards. In a follow-up study we found people who were more paranoid endorsed conspiracies about mask-wearing and potential vaccines – again, mask attitude and conspiratorial beliefs were associated with erratic task behaviour and changed priors. Future public health responses to the pandemic might leverage these observations, mollifying paranoia and increasing adherence by tempering people’s expectations of other’s behaviour, and the environment more broadly, and reinforcing compliance.

A translational approach for NMDA receptor profiling as a vulnerability biomarker for depression and schizophrenia

NEW FINDINGS

What is the central question of this study? Can the change in plasma arginine vasopressin concentration (P_[AVP] ) in response to osmotic stimulation (P_Osm ) serve as a biomarker for NMDA receptor signalling in schizophrenia and depression and thereby distinguish between these mental illnesses? What is the main finding and its importance? In response to hyperosmotic challenge, depressed subjects showed increased P_[AVP] response compared with healthy control and schizophrenic subjects. However, schizophrenic subjects were not different from healthy control subjects in this small sample. The 'P_[AVP] response to P_Osm ' is a suitable biomarker to distinguish depressed versus schizophrenic patients when used with psychiatric screening. This is the first objective physiological measure for schizophrenia or depression. Altered NMDA receptor activity and glutamate signalling might underlie the pathogenesis of both schizophrenia and depression in subgroups of patients. In schizophrenia, pharmacological modelling, post-mortem and imaging data suggest reduced NMDA signalling. In contrast, recent clinical trials demonstrating the efficacy of the NMDA antagonist ketamine in severely depressed patients suggest increased NMDA receptor signalling. We conducted a proof-of-concept study to assess whether there is any in vivo evidence for an inverse association in depression and schizophrenia with respect to the NMDA receptor function. For this purpose, we used a translational approach, based on findings from animal studies that NMDA receptor is a key mediator of arginine vasopressin (AVP) release into the bloodstream. Using hypertonic saline to increase plasma osmolality (P_Osm ) and thereby induce AVP release, as done in animal studies, we found that in depressed patients the NMDA receptor-mediated AVP release induced by hypertonic saline infusion was significantly increased [0.24 (0.15) pg ml^-1  mosmol^-1 , P < 0.05] compared with schizophrenia patients [0.07 (0.07) pg ml^-1  mosmol^-1 ]. Slopes for healthy control subjects were 0.11 (0.09) pg ml^-1  mosmol^-1 which was less than the depressed group. These findings are consistent with implicated NMDA receptor-related abnormalities in depression and schizophrenia in subgroups of patients and provide the first in vivo evidence of this dichotomy.

Subcortical volumetric abnormalities in bipolar disorder

Considerable uncertainty exists about the defining brain changes associated with bipolar disorder (BD). Understanding and quantifying the sources of uncertainty can help generate novel clinical hypotheses about etiology and assist in the development of biomarkers for indexing disease progression and prognosis. Here we were interested in quantifying case-control differences in intracranial volume (ICV) and each of eight subcortical brain measures: nucleus accumbens, amygdala, caudate, hippocampus, globus pallidus, putamen, thalamus, lateral ventricles. In a large study of 1710 BD patients and 2594 healthy controls, we found consistent volumetric reductions in BD patients for mean hippocampus (Cohen's d=-0.232; P=3.50 × 10-7) and thalamus (d=-0.148; P=4.27 × 10-3) and enlarged lateral ventricles (d=-0.260; P=3.93 × 10-5) in patients. No significant effect of age at illness onset was detected. Stratifying patients based on clinical subtype (BD type I or type II) revealed that BDI patients had significantly larger lateral ventricles and smaller hippocampus and amygdala than controls. However, when comparing BDI and BDII patients directly, we did not detect any significant differences in brain volume. This likely represents similar etiology between BD subtype classifications. Exploratory analyses revealed significantly larger thalamic volumes in patients taking lithium compared with patients not taking lithium. We detected no significant differences between BDII patients and controls in the largest such comparison to date. Findings in this study should be interpreted with caution and with careful consideration of the limitations inherent to meta-analyzed neuroimaging comparisons.

Sol-Gel-Derived Thin Films Incorporating An Organic Second-Order NLO Compound With Large βμ

We have synthesized a new second-order NLO compound containing both the highly active tricyanovinyl electron acceptor group and appropriate funtionality for covalent bonding to an inorganic silica matrix by sol-gel processing. Sub-Micron films of this material can be prepared by spin-coating, and thicker films can be prepared by casting or by spinning multiple layers. After curing at 150 °C, these films exhibit good chemical durability. The chromophores can be aligned by either corona or parallel-plate poling during the curing process. In this paper we will discuss the synthesis of the NLO compounds; sol-gel processing and thin-film preparation; optical, thermal, and chemical properties of the films; and the results of both corona and parallel-plate poling experiments.

CpG-C ISS-ODN activation of blood-derived B cells from healthy and chronic immunodeficiency virus-infected macaques

Cytosine-phosphate-guanine class C (CpG-C) immunostimulatory sequence oligodeoxynucleotides (ISS-ODNs) activate human B cells and dendritic cells (DCs), properties that suggest potential use as a novel adjuvant to enhance vaccine efficacy. After demonstrating that the CpG-C ISS-ODN C274 activates macaque DCs, we examined in vitro activation of macaque B cells by C274 as a prelude to evaluation of this molecule as an adjuvant in the testing of candidate human immunodeficiency virus vaccines in the rhesus macaque-simian immunodeficiency virus (SIV) model. C274 induced macaque CD20(+) B cells to proliferate more strongly than CD40 ligand or CpG-B ISS-ODN. C274 enhanced B cell survival; increased viability was most evident after 3-7 days of culture. Increased expression of CD40, CD80, and CD86 by B cells was apparent within 24 h of exposure to C274 and persisted for up to 1 week. C274-stimulated, B cell-enriched and peripheral blood mononuclear cell suspensions from naïve and immunodeficiency virus-infected monkeys secreted several cytokines [e.g., interleukin (IL)-3, IL-6, IL-12, interferon-alpha] and chemokines [e.g., monocyte chemoattractant protein-1/CC chemokine ligand 2 (CCL2), macrophage-inflammatory protein-1alpha/CCL3, IL-8/CXC chemokine ligand 8]. In comparison, exposure of macaque B cells to SIV had minimal impact on surface phenotype, despite inducing cytokine and chemokine production in cells from infected and uninfected animals. These observations emphasize the need to identify strategies to optimally boost immune function, as immunodeficiency viruses themselves only partially activate B cells and DCs. The ability of C274 to stimulate B cells and DCs in healthy and infected monkeys suggests its possible use as a broad-acting adjuvant to be applied in the rhesus macaque model for the development of preventative and therapeutic vaccines.

Dendritic cells and HIV infection: activating dendritic cells to boost immunity

Dendritic cells (DCs) are white blood cells that coordinate innate and adaptive immunity. They are distributed within epithelia and mucosal-associated lymphoid tissues, positioned to entrap incoming pathogens or vaccines. Human immunodeficiency virus (HIV) and the non-human primate equivalent (SIV) exploit DCs to amplify infection, underscoring the need to harness strategies that promote presentation of virus by DCs to stimulate potent anti-viral immunity instead of virus transmission. Two main subsets of DCs need to be considered: myeloid (MDC) and plasmacytoid (PDC) subsets. Using the SIV-macaque system to advance oral vaccine research, we examined macaque PDC and MDC biology, identifying ways to activate DCs and boost antiviral immunity. Immunostimulatory oligodeoxyribonucleotides (ISS-ODNs) stimulated PDC/MDC mixtures to up-regulate co-stimulatory molecule expression and to secrete both IFN-alpha and IL-12. Additionally, ISS-ODNs augmented SIV-specific IFN-gamma responses induced by virus-bearing DCs. ISS-ODN-driven DC activation is being pursued to improve oral/nasopharyngeal mucosal vaccines and therapies against HIV.

Antibody formation against beta-tubulin class III in response to brain trauma

Brain trauma typically leads to neuronal damage and loss. Assuming a transient autoimmune response to debris of the damaged neurones, we have monitored serum titres of IgG and IgM antibodies to beta-tubulin class III (betaTcIII), which is almost exclusively found in neuronal cytoskeletons. In 15 out of 18 patients, the peak of the IgG or IgM antibody titre appeared in the serum within 3 weeks of a brain trauma.

Characterization and isolation of novel microsatellites from the Drosophila dunni subgroup

We have isolated and characterized 77 novel microsatellites from two species, Drosophila dunni and Drosophila nigrodunni, which are closely related Caribbean-island endemics from the Drosophila cardini species group. These species are very distantly related to all other Drosophila from which microsatellites have previously been characterized. We find that the average length of microsatellites isolated in these species is quite small, with an overall mean length of 9.8 repeat units for dinucleotide microsatellites in the two study species. The nucleotide composition of dinucleotides differs between the two species: D. nigrodunni has a predominance of (AC/GT)n repeats, whereas D. dunni has equal numbers of (AC/GT)n and (AG/CT)n repeats. Tri- and tetranucleotide repeats are not abundant in either species. We assayed the variability of eight microsatellites in a closely related third species, Drosophila arawakana, using wild-caught individuals from the island of Guadeloupe. We found the microsatellites to be extremely variable in this population, with observed heterozygosities ranging from 0.541 to 0.889. DNA amplification trials suggest that these eight microsatellites are widely conserved across the D. cardini group, with five of the eight producing amplification products in every species tested. However, the loci are very poorly conserved over greater phylogenetic distances. DNA amplification of the microsatellite loci was unreliable in members of the closely related Drosophila quinaria, Drosophila calloptera, Drosophila guarani and Drosophila tripunctata species groups. Furthermore, these microsatellites could not be detected in the genome of Drosophila melanogaster, despite the conservation of microsatellite flanking regions at some loci. These data indicate that Drosophila microsatellite loci are quite short lived over evolutionary timescales relative to many other taxa.

Physical mapping of the mouse tilted locus identifies an association between human deafness loci DFNA6/14 and vestibular system development

The tilted (tlt) mouse carries a recessive mutation causing vestibular dysfunction. The defect in tlt homozygous mice is limited to the utricle and saccule of the inner ear, which completely lack otoconia. Genetic mapping of tlt placed it in a region orthologous with human 4p16.3-p15 that contains two loci, DFNA6 and DFNA14, responsible for autosomal dominant, nonsyndromic hereditary hearing impairment. To identify a possible relationship between tlt in mice and DFNA6 and DFNA14 in humans, we have refined the mouse genetic map, assembled a BAC contig spanning the tlt locus, and developed a comprehensive comparative map between mouse and human. We have determined the position of tlt relative to 17 mouse chromosome 5 genes with orthologous loci in the human 4p16.3-p15 region. This analysis identified an inversion between the mouse and human genomes that places tlt and DFNA6/14 in close proximity.

The management of depression: the implications for managed care--roundtable discussion: Part 3

From the standpoint of managed care, the rising cost of depression can be addressed in multiple ways. In the final portion of the roundtable discussion, the faculty discuss not only disease management programs for depression, but other initiatives health plans (including at the pharmacy level) are undertaking to address the rising costs associated with depression. They also discuss the effect of mental health coverage "parity" laws, which can be expected to drive costs even higher.

Microtubule-associated protein 1B is a component of cortical Lewy bodies and binds alpha-synuclein filaments

Lewy bodies, neuropathological hallmarks of Parkinson's disease and dementia with Lewy bodies, comprise alpha-synuclein filaments and other less defined proteins. Characterization of Lewy body proteins that interact with alpha-synuclein may provide insight into the mechanism of Lewy body formation. Double immunofluorescence labeling and confocal microscopy revealed approximately 80% of cortical Lewy bodies contained microtubule-associated protein 1B (MAP-1B) that overlapped with alpha-synuclein. Lewy bodies were isolated using an immunomagnetic technique from brain tissue of patients dying with dementia with Lewy bodies. Lewy body proteins were resolved by polyacrylamide gel electrophoresis. Immunoblotting confirmed the presence of MAP-1B and alpha-synuclein in purified Lewy bodies. Direct binding studies revealed a high affinity interaction (IC(50) approximately 20 nm) between MAP-1B and alpha-synuclein. The MAP-1B-binding sites were mapped to the last 45 amino acids of the alpha-synuclein C terminus. MAP-1B also bound in vitro assembled alpha-synuclein fibrils. Thus, MAP-1B may be involved in the pathogenesis of Lewy bodies via its interaction with monomeric and fibrillar alpha-synuclein.

Reversible conversion of monomeric human prion protein between native and fibrilogenic conformations

Prion propagation involves the conversion of cellular prion protein (PrPC) into a disease-specific isomer, PrPSc, shifting from a predominantly alpha-helical to beta-sheet structure. Here, conditions were established in which recombinant human PrP could switch between the native alpha conformation, characteristic of PrPC, and a compact, highly soluble, monomeric form rich in beta structure. The soluble beta form (beta-PrP) exhibited partial resistance to proteinase K digestion, characteristic of PrPSc, and was a direct precursor of fibrillar structures closely similar to those isolated from diseased brains. The conversion of PrPC to beta-PrP in suitable cellular compartments, and its subsequent stabilization by intermolecular association, provide a molecular mechanism for prion propagation.

Three-dimensional reconstruction of the mammalian centriole from cryoelectron micrographs: the use of common lines for orientation and alignment

The microtubule organizing center of the animal cell (S. D. Fuller et al., 1992, Curr. Opin. Struct. Biol. 2, 264-274; D. M. Glover et al., 1993, Sci. Am. 268, 62-68; E. B. Wilson, 1925), (The Cell in Development and Heredity) comprises two centrioles and the pericentriolar material. We have completed several three-dimensional reconstructions of individual centrioles from tilt series of cryoelectron micrographs. The reconstruction procedure uses minimization of the common lines residual to define the orientation of the centriolar minefold symmetry axis and then uses this symmetry to generate a structure by weighted backprojection to 28-nm resolution. Many of the features of these reconstructions agree with previous, conventional transmission electron microscopy studies (M. Paintrand et al., 1992, J. Struct. Biol. 108, 107-128). The microtubule barrel of the centriole is roughly 500 nm long and 300 nm in diameter and the microtubule bundles appear to taper toward the distal end. In addition, we see a handedness to the pericentriolar material at the base (distal end) of the centriole which is opposite to the skew of the microtubule triplets. The region at which the microtubule barrel joins this base is intriguingly complex and includes an internal cylindrical feature which is a site of gamma tubulin localization.

Endotoxin tolerance after severe injury and its regulatory mechanisms

OBJECTIVE

To study the responsiveness of peripheral blood mononuclear cells to lipopolysaccharide (LPS) after severe trauma and its regulatory mechanisms.

MATERIALS AND METHODS

The release of proinflammatory reacting cytokines (tumor necrosis factor-alpha, interleukin (IL)-1 beta, IL-6, IL-8, interferon (IFN)-gamma) into whole blood from 12 patients on day 1, 5, 10, and 14 after severe trauma (Injury Severity Score, 39.3 +/- 2.8 points) and 10 healthy volunteers was studied after stimulation with LPS, concanavalin A, phorbol myristate acetate (PMA), and the addition of recombinant IFN-gamma.

MAIN RESULTS

Trauma caused a significant reduction of LPS and concanavalin A induced release of inflammation activating cytokines into whole blood, including IFN-gamma. However, the diminished release of proinflammatory cytokines could be increased with recombinant IFN-gamma or even attenuated after stimulation of peripheral blood mononuclear cells with the protein kinase C activator PMA.

CONCLUSIONS

Trauma leads to reduced responsiveness of blood monocytes to LPS and a decreased secretion of proinflammatory reacting lymphokines. Because activation of the protein kinase C pathway with PMA or the addition of IFN-gamma significantly increased cytokine response, endotoxin tolerance is not caused by inhibition of protein synthesis, but to disturbances in the signal transduction pathway and its regulating mediators.

Different pattern of local and systemic release of proinflammatory and anti-inflammatory mediators in severely injured patients with chest trauma

BACKGROUND

Excessive release of proinflammatory cytokines has been involved in pathogenesis of acute respiratory distress syndrome.

DESIGN

Since injured patients with chest trauma reveal a high risk for posttraumatic acute respiratory distress syndrome, local and systemic release of proinflammatory cytokines and their naturally occurring inhibitors were determined in the early posttraumatic period.

MATERIALS AND METHODS

Proinflammatory and anti-inflammatory mediators were measured in plasma and bronchoalveolar lavage fluid (BALF) from 16 patients with multiple injuries including severe chest injury (Injury Severity Score of 34.4 +/- 2.3 points) and compared with healthy volunteers (n = 17).

RESULTS

Tumor necrosis factor-alpha was detectable neither in plasma nor in BALF. Interleukin-1beta and interleukin-8 were significantly increased in BALF from injured patients, while plasma levels were similar in both groups. Soluble tumor necrosis factor receptors p55 and p75 and interleukin-1ra were markedly elevated in plasma (p < or = 0.01) and BALF (p < or = 0.001) from injured patients compared with controls.

CONCLUSION

Highly increased concentrations of proinflammatory cytokines in BALF, but not in circulation, indicate a strong local inflammatory response early after multiple injuries combined with chest injury rather than severe systemic inflammation. In contrast, anti-inflammatory mechanisms seem to be activated locally and systemically.

Downregulation of proinflammatory cytokine release in whole blood from septic patients

Using animal models or healthy volunteers, injection of lipopolysaccharide (LPS) or bacteria causes activation of macrophages with excessive synthesis and secretion of proinflammatory cytokines. Although these models mimic the effects of LPS in the host, they may represent more of an experimental expression of endotoxemia than natural infection itself. Therefore, as an ex vivo model of sepsis, whole blood from 15 patients with severe sepsis and 20 control patients without infection was stimulated with LPS to study the kinetics of mRNA expression and release of proinflammatory cytokines, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, and IL-6. Stimulation of whole blood with 1 microgram/mL LPS resulted in a maximum increase of cytokine secretion in the control group, while a marked (P < .01) depression of TNF-alpha, IL-1 beta, and IL-6 release was observed in the septic group, which persisted up to 10 days after study enrollment. While IL-1 beta mRNA expression was similar in peripheral blood mononuclear cells (PBMCs) harvested from LPS-stimulated whole blood in septic and control patients, the half-life and consequently the expression of TNF-alpha and IL-6 mRNA were strongly reduced in the septic group. These data indicate a downregulatory mechanism of cytokine release in whole blood from patients with severe sepsis that occurs on different levels. Although excessive secretion of proinflammatory cytokines has been considered deleterious for the host, the reduced capacity of PBMCs in whole blood from septic patients to synthesize and secrete proinflammatory cytokines to an inflammatory stimulus may result in immunodeficiency, because these cytokines in low concentrations are involved in the upregulation of essential cellular and humoral immune functions.

MR assessment of radiation-induced blood-brain barrier permeability changes in rat glioma model

PURPOSE

To assess the potential of a T1-weighted, gadolinium-enhanced MR technique for quantifying radiation-induced changes of blood-brain barrier permeability in a model of stereotactically implanted intracerebral gliomas in rats.

METHODS

We calculated the gadolinium blood-to-tissue transport coefficient for gadopentetate dimeglumine from signal intensities in sequential MR images in nine control animals that were not irradiated and in five and three animals that had received 2500 cGy and 1500 cGy whole-brain irradiation, respectively, at 2 days before imaging.

RESULTS

The average blood-to-tissue transport coefficient values were 9.76 mL.kg-1.min-1 in the control group, 23.41 mL.kg-1.min-1 in the 2500 cGy group, and 25.63 mL.kg-1.min-1 in the 1500-cGy group. Blood-to-tissue transport coefficients were significantly higher after irradiation, indicating increased radiation-induced blood-brain barrier permeability. Similar increased blood-brain barrier leakiness in brain tumors after high-dose irradiation has been shown by previous nuclear medicine studies using quantitative autoradiography.

CONCLUSION

Contrast-enhanced dynamic MR of brain gliomas is a sensitive method to document radiation-induced blood-brain barrier breakdown. Quantitative gadolinium-enhanced MR may become a useful tool for the management of patients with brain tumors undergoing radiation therapy.

Enhanced release of elastase is not concomitant with increased secretion of granulocyte-activating cytokines in whole blood from patients with sepsis

BACKGROUND

The proteolytic enzyme elastase released by granulocytes (polymorphonuclear leukocytes [PMN]) in high concentrations during sepsis causes degradation of essential plasma proteins, endothelial damage, and tissue edema. This may result in organ dysfunction and organ failure during sepsis, since increased elastase plasma levels correlate with the mortality rate of patients with sepsis. In vitro studies demonstrated a regulatory role of inflammatory cytokines (tumor necrosis factor-alpha [TNF-alpha], interleukin 1 beta [IL-1 beta], IL-8]) upregulating protease release by PMN. In this light, the interactions between cytokine release by macrophages and altered elastase secretion during sepsis remain to be determined.

METHODS

An ex vivo model consisting of lipopolysaccharide stimulation of human whole blood as a relevant physiological milieu was used. Heparinized blood was obtained from 20 patients with sepsis syndrome (APACHE II [Acute Physiology and Chronic Health Evaluation II] score 28.5 +/- 1.2 points [mean +/- SD]) on days 0 through 3, 5, 7, and 10 after sepsis diagnosis and from 20 control patients without infection. Blood was incubated with lipopolysaccharide (1 mg/L) for 8 hours. Plasma levels of elastase, TNF-alpha, IL-1 beta, and IL-8 were determined using enzyme-linked immunosorbent assay or bioassay (TNF-alpha), respectively.

RESULTS

Elastase plasma levels in whole blood from patients with sepsis were increased up to 188% (P < .01) above normal, while the release of TNF-alpha (-87%), IL-1 beta (-91%), and IL-8 (-51%) was markedly (P < .01) decreased compared with control patients. Neutralization of TNF-alpha or IL-1 beta did not attenuate the increased release of elastase.

CONCLUSIONS

These data indicate an increased release of elastase by PMN despite a reduced secretion of PMN-activating cytokines. Although priming effects of TNF-alpha, IL-1 beta, and IL-8 on protease secretion in vivo cannot be excluded completely, other mediators or mechanisms may be involved in the upregulation of detrimental protease release during sepsis.

Regulation of interleukin 8 gene expression by oxidant stress

Interleukin 8 (IL-8) is a recently described cytokine that functions as a potent neutrophil chemoattractant and activator. We sought to examine the link between the generation of reactive oxygen intermediates (ROI) and the regulation of IL-8 gene expression to specifically test the hypothesis that ROI would induce production of IL-8 mRNA and protein. In lipopolysaccharide-stimulated human whole blood, the OH radical scavenger dimethyl sulfoxide (Me2SO) dramatically inhibited (approximately 90%) IL-8 production, but had minimal effects on the production of tumor necrosis factor, interleukin 1 beta (IL-1), and IL-6. To determine whether NADPH-oxidase-generated free radicals were critical in the regulation of IL-8, studies were performed using blood from patients with chronic granulomatous disease. In both normal individuals and patients with chronic granulomatous disease, production of IL-8 could be initiated with lipopolysaccharide, phytohemagglutinin, or aggregated immune complexes, and this production could be inhibited by Me2SO (1% v/v). To examine if oxidant stress represents a ubiquitous mechanism for the induction of IL-8, experiments were performed in cultured cell lines. In the human hepatoma cell line Hep-G2, Me2SO dose-dependently inhibited tumor necrosis factor-stimulated IL-8 production, with a 74 +/- 1% reduction observed at a Me2SO concentration of 1%. Direct exposure to ROI demonstrated that H2O2 stimulated IL-8 production in a dose-dependent manner in Hep-G2 cells, A549 pulmonary type II epithelial cells, and human skin fibroblasts; this induction could be prevented by addition of catalase. The production of IL-8 appeared to be specific to an oxidant stress since exposure of the cells to heat shock or chemical stress did not induce expression of IL-8. These studies demonstrate that oxidant stress is an important regulator of IL-8 gene expression and support the hypothesis that low levels of ROI may serve to initiate IL-8 production which then serves to recruit neutrophils to sites of inflammation.

Measurement of blood-brain barrier permeability in a tumor model using magnetic resonance imaging with gadolinium-DTPA

Sequential MR imaging with gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) and sequential measurements of plasma Gd-DTPA concentration by inductively coupled plasma atomic emission spectroscopy (ICP-AES) were used to estimate the blood-to-tissue transport coefficient (Ki) in the 36B-10 rat glioma model. For these measurements, tissue Gd-DTPA concentration was estimated from tumor enhancement by correlation with calibration measurements obtained by ICP-AES analysis of tumor tissue. The 14 animals for which Ki was calculated can be grouped into those imaged at 11 days following tumor implantation, at 13-18 days, and at 20 days. The mean (+SEM) Ki values for these groups were 1.1 + 0.24, 9.2 + 0.8, and 13.4 + 1.7 ml/kg-min, respectively. These results correspond well with published data obtained by quantitative autoradiography. It is concluded that frequent sequential imaging and a graphical approach to Ki calculation are promising methods for determining the blood-to-tissue transport coefficient noninvasively by contrast-enhanced MRI.

Dyke Award Paper. Kinetics of pathologic blood-brain-barrier permeability in an astrocytic glioma using contrast-enhanced MR

PURPOSE

The feasibility of measuring blood-brain barrier permeability was studied in a 36B-10 brain glioma model in rats.

MATERIALS AND METHODS

In stage I of our study, sequential MR images of glioma-implanted rats were obtained following intravenous administration of three contrast agents of different molecular sizes--Gd-DTPA, polylysine-(Gd-DTPA), and albumin-(Gd-DTPA). In a second set of experiments, sequential MR imaging with Gd-DTPA, quantitative measurements of plasma Gd-DTPA concentration, and postmortem tumor Gd-DTPA measurements were used to estimate the blood-to-tissue transport coefficient (Ki) in the rat glioma model at 11 and 15 days postimplantation.

RESULTS

In stage I, Gd-DTPA caused rapid and greatest tumor enhancement with a significant washout from the tumor during the 120-min experiment. Tumor enhancement using polylysine-(Gd-DTPA) occurred later and was significantly less compared to Gd-DTPA. Tumor signal intensity increased only slowly over time and the peak level of enhancement was least using albumin-(Gd-DTPA). In stage II, the mean (+/- 1 SD) Ki values were 1.1 +/- .24 at 11 days, and 9.3 +/- .8 at 15 days postimplantation. These results correspond well with published data obtained by autoradiography.

CONCLUSION

We believe that the differential enhancement pattern using contrast agents of different molecular sizes reflects a differential permeability of the pathologic blood-brain barrier, and that our studies demonstrate the feasibility of using frequent sequential images and a graphical approach to Ki calculation to determine the blood-to-tissue transport coefficient using contrast-enhanced MR.

Endotoxin and cytokine profile in plasma of baboons challenged with lethal and sublethal Escherichia coli

This descriptive study compares the inflammatory, coagulant, and hemodynamic responses of the baboon to a 2-hr infusion of lethal and sublethal concentrations of Escherichia coli (40 and 4.0 billion organisms per kilogram, respectively). The response to lethal E. coli challenge occurred in three stages: an inflammatory stage marked by a fall in white blood cell count (0-2 hr), a coagulant stage marked by a fall in fibrinogen concentration (2-6 hr), and a hypoxic cell injury stage marked by a rise in SGPT/BUN and by a gradual cardiovascular collapse, and death (6-24 hr). The inflammatory, or first stage coincided with the appearance in plasma of tumor necrosis factor (TNF) and interleukin-1 beta (IL-1 beta), which peaked at 120 and 240-300 min, respectively; a slow but continuous appearance and rise of interleukin-6 (IL-6); and the appearance of endotoxin reaching a maximum at 120 min. This contrasted markedly with the response to sublethal E. coli, in which only one of the three stages was observed (inflammatory) and only minor amounts of the cytokines or endotoxin appeared in the plasma. This study describes the cytokine and endotoxin profiles and the bacteremia in the primate under experimental conditions. It shows for the first time the extreme qualitative differences in their response to lethal and sublethal concentrations of E. coli. It raises the possibility that lethality is associated with an override of the tissue threshold for processing these mediators, as marked by their appearance in plasma in response to lethal E. coli infusion.

Basic fibroblast growth factor levels in the vitreous of patients with proliferative diabetic retinopathy

A two-site enzyme-linked immunosorbent assay was used to quantitate levels of basic fibroblast growth factor in the vitreous from 36 patients undergoing vitrectomy for a variety of retinal conditions, including proliferative diabetic retinopathy, macular pucker, and retinal detachment with and without proliferative vitreoretinopathy. Basic fibroblast growth factor levels ranged from undetectable to 52 ng/mL. In patients with proliferative diabetic retinopathy, basic fibroblast growth factor levels were greater than or equal to 30 ng/mL in 8 of 17 specimens. Of the 8 patients with elevated basic fibroblast growth factor levels, 6 had evidence of active proliferative disease (ie, neovascularization of the disc or iris), whereas in the patients who had undetectable levels only 2 of 9 had evidence of neovascularization of disc and none had neovascularization of the iris. In the rhegmatogenous retinal detachment group, 2 of 10 eyes had elevated basic fibroblast growth factor levels, while none in the macular pucker group had elevated levels. Our study documents increased levels of basic fibroblast growth factor in vitreous specimens from patients with proliferative diabetic retinopathy, particularly those with active proliferative retinopathy. The role of basic fibroblast growth factor in the pathogenesis of various retinal disease entities is discussed.

The latissimus dorsi free flap for coverage of sacral radiodermatitis in the ambulatory patient

Ambulatory patients with large sacral ulcers can represent extremely challenging coverage problems. Technical options become fewer when sacral ulcers are coupled with radiation dermatitis. Latissimus dorsi free flap transfer, with direct anastomoses to sacral vessels, is described in 2 patients.

A unique family of endothelial cell polypeptide mitogens: the antigenic and receptor cross-reactivity of bovine endothelial cell growth factor, brain-derived acidic fibroblast growth factor, and eye-derived growth factor-II

Bovine brain, hypothalamus, pituitary, and retina contain potent anionic polypeptide mitogens for endothelial cells. Immunological assays using murine monoclonal antibodies against bovine endothelial cell growth factor (ECGF) and radioreceptor assays using [125I]ECGF were performed to determine the cross-reactivity of ECGF with bovine acidic pI brain-derived fibroblast growth factor (acidic FGF) and bovine eye-derived growth factor-II [EDGF-II). We observed that acidic FGF and EDGF-II are recognized by anti-ECGF monoclonal antibodies and compete with [125I] ECGF for receptor occupancy. Furthermore, the biological activity of ECGF, acidic FGF, and EDGF-II is potentiated by the glycosaminoglycan, heparin. These results argue that ECGF, acidic FGF, and EDGF-II belong to a common family of polypeptide growth factors.

Isoelectric fractionation and some properties of a protease from soyabean seeds

A protease, capable of hydrolysing benzoyl DL‐arginine p‐nitroanilide(BAPA), and L‐amino acid β‐naphthylamide derivatives, was purified, by isoelectric focusing in the region pH 3–6, from dormant and 6‐day germinated soyabean seeds. The enzyme was focused at pH 4·80. The Km value using BAPA as substrate was found to be 5·03 × 10−4M. Maximum activity of the enzyme towards BAPA was obtained in the pH 8·2–8–5 region. Slight activation was observed in the presence of 0·05 M concentration of Ca2+ and Mg2+ ions. The protease lacked caseinolytic activity, and was not inhibited by Kunitz soyabean trypsin inhibitor.