School Connectedness and Mental Health Among Black Adolescents

Black students' school experiences are important for their mental health. The current study explored the link between school connectedness in middle childhood and depressive symptoms and aggressive behaviors among Black adolescents. Participants were Black youth (Mage = 9.36 years, SD = 0.38 at time 1), (Mage = 15.59 years, SD = 0.60 at time 2), and 50.2% female. The findings demonstrated a significant association between school connectedness assessed at age nine and reduced depressive symptoms and aggressive behaviors reported at age fifteen. Notably, gender moderated the relationship between school connectedness and depressive symptoms, with a stronger association found for girls. These results offer valuable insights into how early perceptions of school connectedness impact the mental health of Black adolescents as they grow older. These findings also indicate that girls might be more attuned to the social and emotional aspects of their schools. These findings validate the significance of a sense of connection to school with mental health outcomes among Black adolescents and indicate the possibility of school connectedness interventions to enhance their overall well-being.

Development and Evaluation of Ensemble Learning-based Environmental Methane Detection and Intensity Prediction Models

The environmental impacts of global warming driven by methane (CH4) emissions have catalyzed significant research initiatives in developing novel technologies that enable proactive and rapid detection of CH4. Several data-driven machine learning (ML) models were tested to determine how well they identified fugitive CH4 and its related intensity in the affected areas. Various meteorological characteristics, including wind speed, temperature, pressure, relative humidity, water vapor, and heat flux, were included in the simulation. We used the ensemble learning method to determine the best-performing weighted ensemble ML models built upon several weaker lower-layer ML models to (i) detect the presence of CH4 as a classification problem and (ii) predict the intensity of CH4 as a regression problem. The classification model performance for CH4 detection was evaluated using accuracy, F1 score, Matthew's Correlation Coefficient (MCC), and the area under the receiver operating characteristic curve (AUC ROC), with the top-performing model being 97.2%, 0.972, 0.945 and 0.995, respectively. The R 2 score was used to evaluate the regression model performance for CH4 intensity prediction, with the R 2 score of the best-performing model being 0.858. The ML models developed in this study for fugitive CH4 detection and intensity prediction can be used with fixed environmental sensors deployed on the ground or with sensors mounted on unmanned aerial vehicles (UAVs) for mobile detection.

Reflecting on change: Critical consciousness as a protective factor for Black youth

OBJECTIVES

The previous decade has seen an abundance of scholarship on the benefits of critical consciousness (CC) for racial and ethnic minority youth. However, it is unclear whether CC is a buffer against the negative effects of racial discrimination on Black adolescents' outcomes. The present study examined whether three CC dimensions buffered against the negative effects of racial discrimination on academic attitudes.

METHOD

A total of 205 Black adolescents (M_age = 15.10) reported racial discrimination and CC. We conducted multiple regression analyses for each component of CC to test for their direct and protective effects on academic attitudes.

RESULTS

Our results revealed associations between CC dimensions and academic attitudes. Critical reflection and critical action also buffered against racial discrimination's negative effects.

CONCLUSIONS

Implications for research on the nature and impact of CC dimensions on racial discrimination and academic attitudes are discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Do We Belong? Examining the Associations Between Adolescents' Perceptions of School Belonging, Teacher Discrimination, Peer Prejudice and Suicide

In the USA, suicide is a leading cause of death for adolescents ages 12 to 18 (National Institute of Mental Health (NIMH), 2019). Given the urgency of this public health crisis, this paper aims to explore the impact of a sense of school belonging and teacher-based discrimination and peer-based prejudice on suicidal ideation and attempts among Black youth. This secondary analysis used a sample of Black youth (N = 4229; M_age = 16) from the National Longitudinal Study of Adolescents to Adult Health data. Independent variables included a sense of school belonging, school-based teacher discrimination, and school-based peer prejudice; the dependent variable was suicidal thoughts and behaviors. The results of multinomial regression analyses revealed that as Black adolescents' sense of school belonging decreased, they were 35% more likely to be at risk for suicidal ideation and attempts. Findings from our study support the assertion that the school microsystem plays a substantial role in modifying the risk of suicidal behavior among Black youth.

Online Racial Discrimination, Critical Consciousness, and Psychosocial Distress Among Black and Latino Adolescents: A Moderated Mediation Model

Past research has found that stressful events such as racial discrimination can spur social development in racially marginalized youth. Critical consciousness has been identified as one such developmental task. Yet, there is still much to learn regarding the role of racial discrimination in developing critical consciousness, particularly as it relates to the mechanism linking racial discrimination to critical consciousness. We examine whether stress, in the form of psychological distress, may explain the link between online racial discrimination and critical consciousness. Online racial discrimination is a type of racial discrimination and is a growing risk to safe internet use for ethnically and racially marginalized youth. The current study employed a moderated mediation model to examine the associations between online racial discrimination and critical consciousness (critical agency and critical action). Data were from 356 Black and Latino adolescents, 50% each (M_age = 15.97, SD = 1.61), and 78.92% female. The model included psychological distress as a mediator between online racial discrimination and critical consciousness and self-esteem as a moderator of psychological distress and two critical consciousness dimensions. Psychological distress was a successful mediator, and self-esteem moderated the link between psychological distress and critical consciousness dimensions. The present findings suggest that psychological distress may be one mechanism through which online racial discrimination may impact the development of critical consciousness in Black and Latino adolescents.

Barriers to School-Based Mental Health Resource Utilization Among Black Adolescent Males

Black adolescent males use available mental health services at a disproportionately lower rate compared to males of other racial groups. This study examines barriers to school-based mental health resource (SBMHR) use among Black adolescent males, as a means of addressing reduced usage of available mental health resources and to improve these resources to better support their mental health needs. Secondary data for 165 Black adolescent males were used from a mental health needs assessment of two high schools in southeast Michigan. Logistic regression was employed to examine the predictive power of psychosocial (self-reliance, stigma, trust, and negative previous experience) and access barriers (no transportation, lack of time, lack of insurance, and parental restrictions) on SBMHR use, as well as the relationship between depression and SBMHR use. No access barriers were found to be significantly associated with SBMHR use. However, self-reliance and stigma were statistically significant predictors of SBMHR use. Participants who identified self-reliance in addressing their mental health symptoms were 77% less likely to use available mental health resources in their school. However, participants who reported stigma as a barrier to using SBMHR were nearly four times more likely to use available mental health resources; this suggests potential protective factors in schools that can be built into mental health resources to support Black adolescent males' use of SBMHRs. This study serves as an early step in exploring how SBMHRs can better serve the needs of Black adolescent males. It also speaks to potential protective factors that schools provide for Black adolescent males who have stigmatized views of mental health and mental health services. Future studies would benefit from a nationally representative sample allowing for more generalizable results regarding barriers and facilitators to Black adolescent males' use of school-based mental health resources.

African-Centered Social Work in the 21st Century: A Content Analysis

Endorsement of African-centered theory and practice are widespread within Black communities across the United States. The usage of African-centered frameworks is also common among many Black social workers. However, past research suggests that African-centered theory and subsequent models of practice are marginalized within social work literature and curricula. Since advocacy began for the inclusion of African-centered approaches to practice during the mid to late 1990s, there have been no strategic analyses tracing how African-centered scholarship has advanced within social work. This study sought to examine to what extent the African-centered framework is included within scholarship among prominent social work journals. A content analysis was conducted of articles in six major social work journals published between 2000 and 2019. A total of 42 articles met the criteria for inclusion. While there has been a level of change in the number of published articles of African-centered social work, findings suggest that relative to other practice modalities/models, African-centered scholarship is noticeably lacking in social work literature. The article concludes with implications to advance culturally responsive research and practice with communities of African descent.

The Mental Health of Black Youth Affected by Community Violence: Family and School Context as Pathways to Resilience

Black youth who experience community violence occupy multiple environments with varying levels of influence on how they display resiliency to prevent adverse mental health outcomes. Considering the recent rise of mental health concerns (i.e., increase in suicidal outcomes) among Black youth, along with the abundance of research illustrating the detrimental impact of community violence, more research is needed to examine how different environmental factors (e.g., family and school) shape how youth protect their mental health while displaying resiliency navigating community violence. The purpose of this study was to examine how family and school contexts predict Black youths' ability to display resiliency to navigate community violence and prevent adverse mental health outcomes. This study utilized a path analysis to examine the associations between parent relationships, parent bonding, school climate, resilience to adverse community experiences, community violence, and mental health among 548 Black adolescents in Chicago. Findings highlight that parent relationships, parent bonding, and school climate influence the association between resilience to community violence and mental health outcomes among Black youth. Implications for mental health practice and policy among Black youth are discussed.

Temperature-dependent infrared and calorimetric studies on arsenicals adsorption from solution to hematite nanoparticles

To address the lack of systematic and surface sensitive studies on the adsorption energetics of arsenic compounds on metal (oxyhydr)oxides, we conducted temperature-dependent ATR-FTIR studies for the adsorption of arsenate, monomethylarsonic acid, and dimethylarsinic acid on hematite nanoparticles at pH 7. Spectra were collected as a function of concentration and temperature in the range 5-50 °C (278-323 K). Adsorption isotherms were constructed from spectral features assigned to surface arsenic. Values of K(eq), adsorption enthalpy, and entropy were extracted from fitting the Langmuir model to the data and from custom-built triple-layer surface complexation models derived from our understanding of the adsorption mechanism of each arsenical. These spectroscopic and modeling results were complemented with flow-through calorimetric measurements of molar heats of adsorption. Endothermic adsorption processes were predicted from the application of mathematical models with a net positive change in adsorption entropy. However, experimentally measured heats of adsorption were exothermic for all three arsenicals studied herein, with arsenate releasing 1.6-1.9 times more heat than methylated arsenicals. These results highlight the role of hydration thermodynamics on the adsorption of arsenicals, and are consistent with the spectral interpretation of type of surface complexes each arsenical form in that arsenate is mostly dominated by bidentate, MMA by a mixture of mono- and bidentate, and DMA by mostly outer sphere.

Framing black boys: parent, teacher, and student narratives of the academic lives of black boys

The discourse on Black boys tends to suggest that Black boys are in complete peril. We begin with evidence that Black boys are excelling in certain contexts (i.e., in certain states, in certain schools, and in certain courses). We then discuss the ways in which the narratives used by parents, teachers, and Black boys themselves may serve to further reinforce views that Black boys are beyond hope. Research on Black parents suggests that they tend to view their sons as vulnerable and have lower expectations for sons than for daughters. Studies of teachers show that they tend to view Black boys as unteachable, as social problems, and as scary. Research on Black boys shows that they are sometimes complicit in supporting these narratives by engaging in negative or ste reotypical behavior. We also include recent research that includes counter-narratives of Black boys. We end with suggestions for future research.

Towards a framework for analysis of eye-tracking studies in the three dimensional environment: a study of visual search by experienced readers of endoluminal CT colonography

OBJECTIVE

Eye tracking in three dimensions is novel, but established descriptors derived from two-dimensional (2D) studies are not transferable. We aimed to develop metrics suitable for statistical comparison of eye-tracking data obtained from readers of three-dimensional (3D) "virtual" medical imaging, using CT colonography (CTC) as a typical example.

METHODS

Ten experienced radiologists were eye tracked while observing eight 3D endoluminal CTC videos. Subsequently, we developed metrics that described their visual search patterns based on concepts derived from 2D gaze studies. Statistical methods were developed to allow analysis of the metrics.

RESULTS

Eye tracking was possible for all readers. Visual dwell on the moving region of interest (ROI) was defined as pursuit of the moving object across multiple frames. Using this concept of pursuit, five categories of metrics were defined that allowed characterization of reader gaze behaviour. These were time to first pursuit, identification and assessment time, pursuit duration, ROI size and pursuit frequency. Additional subcategories allowed us to further characterize visual search between readers in the test population.

CONCLUSION

We propose metrics for the characterization of visual search of 3D moving medical images. These metrics can be used to compare readers' visual search patterns and provide a reproducible framework for the analysis of gaze tracking in the 3D environment.

ADVANCES IN KNOWLEDGE

This article describes a novel set of metrics that can be used to describe gaze behaviour when eye tracking readers during interpretation of 3D medical images. These metrics build on those established for 2D eye tracking and are applicable to increasingly common 3D medical image displays.

Experiences of women referred for urgent assessment of postmenopausal bleeding (PMB)

Women with postmenopausal bleeding (PMB) are referred for specialist assessment within 2 weeks of presentation to their GP. No research has previously examined women's experiences of expedited referral. This was investigated in the present study using questionnaires (6-item State Anxiety Inventory (6-STAI)) and focus groups. A total of 55 women completed questionnaires. Results showed high levels of anxiety at first hospital visit (mean 47.0 (SD 14.27); 95% CI 43.14-50.93). Scores declined by 90 days, but were higher in those not undergoing hysteroscopy. Fifteen women who underwent hysteroscopy attended focus groups. Women recalled fear of cancer from symptom onset until receipt of results. Anxiety was exacerbated by poor knowledge of PMB and lack of awareness of expedited referral. Post-discharge, those with unexplained or recurrent symptoms expressed frustration and upset. Effective strategies to raise awareness of PMB and its causes are needed, including reasons for expedited referral. Women without cancer may also need more support.

The aerobiology of the environment around mechanically ventilated broiler sheds

AIM

To investigate the aerobiology of the environment around mechanically ventilated broiler sheds with the aim of understanding dispersion in the surrounding environment.

METHODS AND RESULTS

Aerosol samples were collected weekly on four different commercial broiler farms through the cycle of 55 days from 2005 to 2007. Samples were collected inside the shed and at varying distances from the sheds. Litter and dust from within the shed were also examined. Members of the genera Staphylococcus (and to a lesser extent Corynebacterium) dominated (10(6) CFU m(-3)) in the outside air at 20 m from the fan and were shown to decrease with distance. At distances of around 400 m, the levels of staphylococci/coryneforms returned to levels typical of those present before the placement of chickens. Escherichia coli levels were low (maximum 100 CFU m(-3)) at 20 m. Fungi were present at uniform levels across the broiler cycle.

CONCLUSIONS

Staphylococci are the dominant organisms present in the air around mechanically ventilated broiler sheds and have the potential to act as an airborne 'marker organism'. SIGNIFICANT IMPACT OF THE STUDY: The outcomes of this study suggest that the impact of aerosols emitted from broiler sheds could be monitored and managed by examining the levels of staphylococci/coryneforms.

P19 Progenitor Cells Progress to Organized Contracting Myocytes After Chemical and Electrical Stimulation:Implications for Vascular Tissue Engineering

PURPOSE

To test the hypothesis that a level of chemical and electrical stimulation exists that allows differentiation of progenitor cells into organized contracting myocytes.

METHODS

A custom-made bioreactor with the capability of delivering electrical pulses of varying field strengths, widths, and frequencies was constructed. Individual chambers of the bioreactor allowed continuous electrical stimulation of cultured cells under microscopic observation. On day 0, 1% dimethylsulfoxide (DMSO), known to differentiate cells into myocytes, was added to P19 progenitor cells. Additionally, for the next 22 days, electrical pulses of varying field strengths (0-3 V/cm), widths (2-40 ms), and frequencies (10-25 Hz) were continuously applied. On day 5, the medium containing DMSO was exchanged with regular medium, and the electrical stimulation was continued. From days 6-22, the cells were visually assessed for signs of viability, contractility, and organization.

RESULTS

P19 cells remained viable with pulsed electrical fields <3 V/cm, pulse widths <40 ms, and pulse frequencies from 10 to 25 Hz. On day 12, the first spontaneous contractions were observed. For individual colonies, local synchronization and organization occurred; multiple colonies were synchronized with externally applied electrical fields.

CONCLUSION

P19 progenitor cells progress to organized contracting myocytes after chemical and electrical stimulation. Incorporation of such cells into existing methods of producing endothelial cells, fibroblasts, and scaffolds may allow production of improved tissue-engineered vascular grafts.

A Novel Culture System Shows that Stem Cells Can be Grown in 3D and Under Physiologic Pulsatile Conditions for Tissue Engineering of Vascular Grafts

BACKGROUND

Currently available vascular grafts have been limited by variable patency rates, material availability, and immunological rejection. The creation of a tissue-engineered vascular graft (TEVG) from autologous stem cells would potentially overcome these limitations. As a first step in creating a completely autologous TEVG, our objective was to develop a novel system for culturing undifferentiated mouse embryonic stem cells (mESC) in a three-dimensional (3D) configuration and under physiological pulsatile flow and pressure conditions.

MATERIALS AND METHODS

A bioreactor was created to provide pulsatile conditions to a specially modified four-well Labtek Chamber-Slide culture system. Undifferentiated mESC were either suspended in a 3D Matrigel matrix or suspended only in cell-culture media within the culture system. Pulsatile conditions were applied to the suspended cells and visualized by video microscopy.

RESULTS

Undifferentiated mESC were successfully embedded in a 3D Matrigel matrix and could withstand physiological pulsatile conditions. Video microscopy demonstrated that the mESC in the 3D matrix were constrained to the wells of the culture system, moved in unison with the applied flows, and were not washed downstream; this was in contrast to the mESC suspended in media alone.

CONCLUSIONS

Undifferentiated mESC can be grown in 3D and under pulsatile conditions. We will use these results to study the effects of long-term pulsatile conditions on the differentiation of mESC into endothelial cells, smooth muscle cells, and fibroblast cells with the long-term goal of creating a completely autologous TEVG.

Hyoid bone position after surgical mandibular advancement

A cephalometric evaluation of the changes in the horizontal and vertical placement of the hyoid bone and of those in the position of the head over the cervical spine after surgical mandibular advancement was undertaken. Seven linear and one angular measurement were investigated in 60 patients, 17 males and 43 females, before and one year after surgical mandibular advancement. The hyoid bone moved forwards horizontally in 78 per cent of the subjects, backwards in 17 per cent, and in 5 per cent of patients it retained its pre-operative position. It moved vertically downwards in 32 per cent of subjects, and in 63 per cent it moved upwards and closer to the body of mandible. The amount of horizontal and vertical change of the hyoid bone was associated with the corresponding change of the mandible after surgery. The vertical change was more distinct in females compared with males. There was variation in the position of the head over the cervical spine; it showed extension in 26.7 per cent of the sample, flexion in 71.7 per cent, and remained the same in only 1.6 per cent after surgery. The results show that with surgical mandibular advancement the hyoid bone follows mainly the advancement of the mandible and moves closer to the body of the mandible. However, there are variations in the changes of hyoid bone and head position that are difficult to predict.

Factors influencing nurses' inferences about patient pain

This study examined the factors that influence nurses' perception of patient pain. Sixteen vignettes were constructed on the basis of interviews with nurses about factors affecting their perception of patient pain and previous published literature. Four variables were systematically varied within a factorial design: diagnosis (surgery vs oncology), level of patient mobility, presence or absence of physical and behavioural signs, and patient gender. Twenty-seven nurses rated each vignette for degree of inferred patient pain and degree of patient psychological distress. Mobility and positive signs of pain had statistically significant effects on nurses' judgments of inferred pain (P < 0.001), but diagnosis had no main effect. Significant interactions showed that: inferred pain in male patients was seen to be greater when immobile while mobility had no effect on the inferred pain of female patients (P < 0.003); oncology patients (compared with surgical patients) had greater inferred pain when displaying positive signs (P < 0.024); and positive signs yielded higher ratings where patients were immobile (P < 0.001). Female patients were perceived to experience higher psychological distress than men (P < 0.037) and oncology patients were perceived to experience higher distress than surgical patients (P < 0.005). Ratings of perceived pain and distress were significantly correlated but did not differ in magnitude. Offered a choice of analgesics to relieve pain for each of the patients depicted, nurses typically chose those with the lowest strength.

Developing the role of the generic healthcare support worker: phase 1 of an action research study

This paper reports on the first phase of an action research practice development project to explore, develop and evaluate the role of the generic healthcare support worker in a high dependency rehabilitation service. The project is being jointly conducted by staff from the University of Southampton, the University of Portsmouth and the Isle of Wight Healthcare NHS Trust and phase 1 is supported by a grant from the NHS Executive (South and West). The aim of phase 1 of the project is to explore the attitudes of staff towards the implementation of the role of the generic healthcare support worker, particularly regarding the practical, professional and ethico-legal problems of the role. Professional and support staff from different parts of the service were interviewed in groups and the interviews were tape recorded, transcribed and subjected to a simple thematic analysis. Four themes emerged from the data relating to the challenge to professional boundaries, being a generic worker, outcomes for service and patients and implementing the role. As an action research project, the aim was not to produce findings that are generalizable beyond the practice areas in which they were generated, but it is nevertheless hoped that the reader might be able to apply some of the conclusions to his or her own setting.

Electrophysiological measures of cognition in biological psychiatry: some cautionary notes

Research into the electrophysiological correlates of mental illness is currently expanding, largely because of the availability of relatively inexpensive and powerful computers. However, improvements in technology do not always lead to enhanced methodological procedures; thus, there are concerns over the proper interpretation of the results of these investigations. Our argument is that electroencephalographic (EEG) research into psychopathology of psychiatric diseases should adopt a cognitivist model of mental dysfunction rather than a neurologist model of brain disease. Cognitive science has significant potential as an integrative framework for theorizing and researching psychiatric disorders and their treatment. Models of human cognitive functioning have rather special and unique features; these will make their impact upon the nature of both the analysis and interpretation of EEG data. The adoption of a sound model of brain function has implications for the methods to be used at different successive stages of the research process. We address a number of methodological requirements pertaining to: the recording and analysis of EEG signals, the laboratory context, the nature of the tasks, and the attribution of obtained effects. However, there are grounds for great caution. Even if the mapping of electrical changes in brain activity leads to a good approximation of the temporal and spatial dynamics of higher brain function, exploitation of such information presupposes a deeper understanding of both human cognition and the physiological basis of the EEG than is often displayed in the literature. To demonstrate this fundamental point, we draw a number of comparisons between traditional neurological approaches to brain assessment and contemporary cognitive psychophysiology.

Will managed care collapse at the hands of the civil justice system? ERISA protection may end

For the first time, instances where HMO strategies to save money collide with the patient's right to receive quality of care have come under the scrutiny of the law.

A psychophysiological inquiry into the nature of the Sokolovian orienting response comparator model: skin conductance and EEG data

The mechanisms which trigger the orienting response (OR) are still the subject of lively debate. Sokolov (1990) proposes the development of a multidimensional model of the physical parameters of stimulation. Recent OR research has shown that the skin conductance OR (SCOR) is related to task demands and controlled processing, although this is not so clear for central physiological indexes of orienting. Seventy-three subjects performed visual discriminations of stimuli within a warning-stimulus paradigm. The physical complexity of stimuli and their task relevance were manipulated within subjects, while the nonspecific effects of workload were controlled with a group factor. SCORs were measured concurrently with 1-s epochs of EEG alpha and theta power from Fz, Cz, Pz, and Oz. Neither index was reliably affected by the physical complexity of stimulation alone. However, both higher task relevance and higher workload significantly increased the magnitude of EEGORs and SCORs. Task averages of central and autonomic activity showed an overall pattern of covariation, but a second-by-second breakdown of EEG spectra suggests that the SCOR may be an aggregate of the activation of diverse brain mechanisms responsible for physiological orienting. The results are consistent with a model of orienting as a continuous dimension of resource allocation to anticipated and current task demands, rather than with the abrupt dichotomy between voluntary and involuntary orienting. Implications for the classical OR Sokolovian model are discussed.

Is sham smoking an adequate control condition for the motoric component of smoking?

This is a study of the similarities and differences between real and sham smoking; 15 participants, all of whom had a smoking history of more than two years, attended on two occasions within a balanced design. They were instructed to either smoke or sham smoke their own brand of cigarette as normally as possible. Real and sham smoking were highly correlated for various measures: frequency of puffs, puff duration, interpuff interval, puff volume, and puff pressure. This showed that the pattern of smoking was common across the two conditions. At the same time, there were differences between the two conditions in the intensity of smoking, such that sham smoking led to significant increases in puff duration, volume, frequency, and decreases in the length of interpuff interval. Sham smoking is often used in smoking experimentation as a control for various aspects of smoking. This is the first study to examine the commonalities between real and sham smoking in a detailed and systematic fashion.

U937 cells can utilize plasminogen activator to regulate human interferon-gamma

Urokinase-type plasminogen activator (uPA) converts the proenzyme plasminogen to plasmin and thereby contributes to processes like cell migration, tissue remodeling, and cytokine processing. We report here that uPA produced by the human U937 promonocytic cell line also initiated the inactivation of recombinant interferon-gamma (rIFN-gamma) by plasmin-mediated proteolysis. When cultured serum-free with plasminogen, U937 promonocytic cells generated measurable levels of plasmin activity and destroyed the antiviral activity of exogenously added rIFN-gamma. This effect was not seen in the absence of plasminogen, was prevented by inhibitors of uPA and plasmin, and was accompanied by changes in the electrophoretic mobility of rIFN-gamma on polyacrylamide gels, consistent with limited proteolysis of the lymphokine. Culturing U937 cells or blood monocytes for 48 h led to an elevated expression of their surface uPA and an increase in their capacity to produce plasmin and inactivate rIFN-gamma. The ability of rIFN-gamma to induce Fc receptors on U937 cells could also be prevented by providing the cells with a source of exogenous plasminogen, indicating that U937 cells could control their own activation in vitro through the action of uPA. The results of these studies support the conclusion that mononuclear phagocytes have the capacity to use uPA to regulate cytokine activity in vitro.

Effects of situational demands on the direction of electrodermal activation during smoking

Task demands (normal smoking; sham smoking; smoking or non-smoking during complex cognitive performance; and, smoking or non-smoking during monotonous vigilance performance) were manipulated in three experiments. Smoking increased electrodermal activity (EDA) arousal from pre-smoking baseline. Sham smoking (as a control for motoric aspects) also increased EDA arousal but to a lesser degree. In contrast the demands of complex cognitive performance were associated with lower EDA arousal during smoking than during non-smoking. Finally, during vigilance performance smoking maintained EDA arousal which during non-smoking decreased. Smoking did not improve performance during complex cognitive processing or vigilance above deprivation performance levels. It was concluded that smoking did have bidirectional effects as a function of task demand. However, there was no evidence that these physiological changes were functional and the smoking behavior data gave no indication as to the cause of these changes.

Motor nerve biopsy in severe Guillain-Barré syndrome

We undertook a biopsy of a terminal branch of the musculocutaneous nerve in a man with severe Guillain-Barré syndrome and very small distally evoked action potentials. The biopsy showed pronounced subperineurial edema, macrophage infiltration, and many axons that had been completely demyelinated, some associated with intratubal macrophages. The biopsy unequivocally identified the pathological process as primary demyelination, not axonal degeneration, and was more informative than previous reports of sural nerve biopsies in patients with Guillain-Barré syndrome.