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Assessment of Selective and Universal Screening for Suicide Risk in a Pediatric Emergency Department. FOCUS (AMERICAN PSYCHIATRIC PUBLISHING) 2023; 21:217-224. [PMID: 37201139 PMCID: PMC10172558 DOI: 10.1176/appi.focus.23021007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Importance According to National Patient Safety Goal 15.01.01, all individuals being treated or evaluated for behavioral health conditions as their primary reason for care in hospitals and behavioral health care organizations accredited by The Joint Commission should be screened for suicide risk using a validated tool. Existing suicide risk screens have minimal or no high-quality evidence of association with future suicide-related outcomes. Objective To test the association between results of the Ask Suicide-Screening Questions (ASQ) instrument in a pediatric emergency department (ED), implemented through selective and universal screening approaches, and subsequent suicide-related outcomes. Design Setting and Participants In this retrospective cohort study at an urban pediatric ED in the United States, the ASQ was administered to youths aged 8 to 18 years with behavioral and psychiatric presenting problems from March 18, 2013, to December 31, 2016 (selective condition), and then to youths aged 10 to 18 years with medical presenting problems (in addition to those aged 8-18 years with behavioral and psychiatric presenting problems) from January 1, 2017, to December 31, 2018 (universal condition). Exposure Positive ASQ screen at baseline ED visit. Main Outcomes and Measures The main outcomes were subsequent ED visits with suicide-related presenting problems (ie, ideation or attempts) based on electronic health records and death by suicide identified through state medical examiner records. Association with suicide-related outcomes was calculated over the entire study period using survival analyses and at 3-month follow-up for both conditions using relative risk. Results The complete sample was 15003 youths (7044 47.0%] male; 10209 [68.0%] black; mean [SD] age, 14.5 [3.1] years at baseline). The follow-up for the selective condition was a mean (SD) of 1133.7 (433.3) days; for the universal condition, it was 366.2 (209.2) days. In the selective condition, there were 275 suicide-related ED visits and 3 deaths by suicide. In the universal condition, there were 118 suicide-related ED visits and no deaths during the follow-up period. Adjusting for demographic characteristics and baseline presenting problem, positive ASQ screens were associated with greater risk of suicide-related outcomes among both the universal sample (hazard ratio, 6.8 [95% CI, 4.2-11.1]) and the selective sample (hazard ratio, 4.8 [95% CI, 3.5-6.5]). Conclusions and Relevance Positive results of both selective and universal screening for suicide risk in pediatric EDs appear to be associated with subsequent suicidal behavior. Screening may be a particularly effective way to detect suicide risk among those who did not present with ideation or attempt. Future studies should examine the impact of screening in combination with other policies and procedures aimed at reducing suicide risk.Appeared originally in JAMA Netw Open 2019; 2:e1914070.
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A Brief Text-Messaging Intervention for Suicidal Youths After Emergency Department Discharge. Psychiatr Serv 2022; 73:954-957. [PMID: 35172597 DOI: 10.1176/appi.ps.202000559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Research has shown that the months after hospital discharge following treatment for suicidal thoughts or behaviors is a high-risk period for suicide. Moreover, the needs of a subset of youths at increased risk for suicide are not being met by community mental health providers, resulting in frequent emergency department (ED) visits. While undertaking a quality improvement effort, the authors' health care system piloted caring text messages to support youths discharged from the hospital after screening positive for suicide risk in the ED. The text-messaging intervention was feasible and acceptable, and youths reported that the messages helped reduce their suicidal thoughts and behaviors postdischarge. The results of this text-messaging intervention prompted the Maryland Department of Health to offer a similar intervention to all Marylanders.
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Suicide Risk Screening in Pediatric Outpatient Neurodevelopmental Disabilities Clinics. J Dev Behav Pediatr 2022; 43:181-187. [PMID: 34657090 DOI: 10.1097/dbp.0000000000001026] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 09/02/2021] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The purpose of this study was to describe the implementation of universal suicide risk screening in pediatric neurodevelopmental disabilities (NDD) medical clinics, analyze demographic and clinical characteristics of eligible patients, describe outcomes of positive screenings, and describe factors that influenced participation in screenings. METHODS A suicide risk screening protocol was developed and implemented for medical clinic patients aged 8 to 18 years. Registered nurses screened patients using the "Ask Suicide-Screening Questions" tool during triage. Positive screenings were referred for further assessment and mental health management. Demographics and clinical data were extracted from medical records using retrospective chart reviews. RESULTS During the 6-month study period, 2961 individual patients presented for 5260 screening eligible patient visits. In total, 3854 (73.3%) screenings were completed with 261 (6.8%) positive screenings noted. Screenings were declined in 1406 (26.7%) visits. Parents of children with cognitive impairments were more likely to decline screening. Clinics serving children with autism spectrum disorder had higher rates of positive screenings compared with all other clinic attendees. Seventy-two of 187 children (38.5%) with positive screenings were identified and referred to outpatient mental health referrals. Seven (2.5%) of these children required acute psychiatric treatment. CONCLUSION Routine screening, identification of increased suicide risk, and referral to mental health care among children with NDD are feasible. It remains unclear whether variation in rates among youth with and without NDD may indicate true differences in suicide risk or cognitive impairments or reflect psychiatric comorbidities. High rates of declined participation may have influenced identification of children with NDD and suicide risk. Preliminary findings identified groups of children with NDD at heightened risk for suicidal ideation and behavior. Further research is needed to assess the validity of suicide risk screening tools in children with neurodevelopmental disorders.
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Ineligibility for and Refusal to Participate in Randomized Controlled Trials That Have Studied Impact on Suicide-Related Outcomes in the United States: A Meta-Analysis. J Clin Psychiatry 2022; 83. [PMID: 35172049 DOI: 10.4088/jcp.20r13798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Objective: Ineligibility for and refusal to participate in randomized controlled trials (RCTs) can potentially lead to unrepresentative study samples and limited generalizability of findings. We examined the rates of exclusion and refusal in RCTs that have studied impact on suicide-related outcomes in the US. Data Sources: PubMed, the Cochrane Library, the Campbell Collaboration Library of Systematic Reviews, CINAHL, PsycINFO, and Education Resources Information Center were searched from January 1990 to May 2020 using the terms (suicide prevention) AND (clinical trial). Study Selection: Of 8,403 studies retrieved, 36 RCTs assessing effectiveness on suicide-related outcomes in youth (≤ 25 years old) conducted in the US were included. Data Extraction: Study-level data were extracted by 2 independent investigators for a random-effects meta-analysis and meta-regression. Results: The study participants (N = 13,264) had a mean (SD) age of 14.87 (1.58) years and were 50% male, 23% African American, and 24% Hispanic. The exclusion rate was 36.4%, while the refusal rate was 25.5%. The exclusion rate was significantly higher in the studies excluding individuals not exceeding specified cutoff points of suicide screening tools (51.2%; adjusted linear coefficient [β] = 1.30, standard error [SE] = 0.15; P = .041) and individuals not meeting the age or school grade criterion (45.9%; β = 1.37, SE = 0.13; P = .005). Conclusions: The rates of exclusion and refusal in youth prevention interventions studying impact on suicide-related outcomes were not as high compared to the rates found in other mental and behavioral interventions. While there was strong racial/ethnic group representation in RCTs examining youth suicide-related outcomes, suicide severity and age limited eligibility.
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Machine Learning and Natural Language Processing in Mental Health: Systematic Review. J Med Internet Res 2021; 23:e15708. [PMID: 33944788 PMCID: PMC8132982 DOI: 10.2196/15708] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 04/18/2020] [Accepted: 10/02/2020] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Machine learning systems are part of the field of artificial intelligence that automatically learn models from data to make better decisions. Natural language processing (NLP), by using corpora and learning approaches, provides good performance in statistical tasks, such as text classification or sentiment mining. OBJECTIVE The primary aim of this systematic review was to summarize and characterize, in methodological and technical terms, studies that used machine learning and NLP techniques for mental health. The secondary aim was to consider the potential use of these methods in mental health clinical practice. METHODS This systematic review follows the PRISMA (Preferred Reporting Items for Systematic Review and Meta-analysis) guidelines and is registered with PROSPERO (Prospective Register of Systematic Reviews; number CRD42019107376). The search was conducted using 4 medical databases (PubMed, Scopus, ScienceDirect, and PsycINFO) with the following keywords: machine learning, data mining, psychiatry, mental health, and mental disorder. The exclusion criteria were as follows: languages other than English, anonymization process, case studies, conference papers, and reviews. No limitations on publication dates were imposed. RESULTS A total of 327 articles were identified, of which 269 (82.3%) were excluded and 58 (17.7%) were included in the review. The results were organized through a qualitative perspective. Although studies had heterogeneous topics and methods, some themes emerged. Population studies could be grouped into 3 categories: patients included in medical databases, patients who came to the emergency room, and social media users. The main objectives were to extract symptoms, classify severity of illness, compare therapy effectiveness, provide psychopathological clues, and challenge the current nosography. Medical records and social media were the 2 major data sources. With regard to the methods used, preprocessing used the standard methods of NLP and unique identifier extraction dedicated to medical texts. Efficient classifiers were preferred rather than transparent functioning classifiers. Python was the most frequently used platform. CONCLUSIONS Machine learning and NLP models have been highly topical issues in medicine in recent years and may be considered a new paradigm in medical research. However, these processes tend to confirm clinical hypotheses rather than developing entirely new information, and only one major category of the population (ie, social media users) is an imprecise cohort. Moreover, some language-specific features can improve the performance of NLP methods, and their extension to other languages should be more closely investigated. However, machine learning and NLP techniques provide useful information from unexplored data (ie, patients' daily habits that are usually inaccessible to care providers). Before considering It as an additional tool of mental health care, ethical issues remain and should be discussed in a timely manner. Machine learning and NLP methods may offer multiple perspectives in mental health research but should also be considered as tools to support clinical practice.
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Lowering the Age Limit in Suicide Risk Screening: Clinical Differences and Screening Form Predictive Ability. J Am Acad Child Adolesc Psychiatry 2021; 60:537-540. [PMID: 33667604 DOI: 10.1016/j.jaac.2020.11.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 11/11/2020] [Accepted: 02/24/2021] [Indexed: 11/17/2022]
Abstract
Our research provides preliminary evidence that suicide risk screening is warranted in patients as young as 8-9 years old presenting to the emergency department (ED) with behavioral and mental health symptoms. The goal of this retrospective cohort study (N = 2,466 unique patient visits) was to assess the value of suicide risk screening in children younger than 10 years old who present to the ED with behavioral and mental health concerns. The Johns Hopkins Hospital pediatric ED began screening with the Ask Suicide-Screening Questions (ASQ) for patients 8-21 years old who presented with a behavioral or mental health concern in March 2013 as ED standard of care. We examined the demographic and clinical differences between younger (8-9 years old; n = 270) and older (10-21 years old; n = 2,196) youths who were screened for suicide risk with the ASQ (from March 13, 2013 through December 31, 2016). In summary, 36% of 8- and 9-year-old patients who came to the ED for behavioral and mental health concerns screened positive for suicide risk on the ASQ. The younger patients who screened positive were more likely to present with externalizing symptoms and hallucinations and less likely to present with suicidal ideation or an attempt than their older counterparts. Importantly, 71.1% of 8- to 9-year-old patients who screened positive did not present to the ED for suicidal ideation or attempt vs 50.1% (614/1,226) of patients older than age 10 years.
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Suicide Screening in Sturge-Weber Syndrome: An Important Issue in Need of Further Study. Pediatr Neurol 2020; 110:80-86. [PMID: 32660870 DOI: 10.1016/j.pediatrneurol.2020.03.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/17/2020] [Accepted: 03/08/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND Sturge-Weber syndrome is a neurocutaneous disorder associated with epilepsy, glaucoma, cognitive impairments, and a port-wine birthmark. Although individuals with Sturge-Weber syndrome are vulnerable to known risk factors for suicide, including chronic illness and physical differences (port-wine birthmark), frequency of suicidal ideation and attempts, and the clinical factors associated with suicide risk, in patients with Sturge-Weber syndrome is unknown. METHODS As a part of routine hospital practice, all outpatients aged eight years and older underwent suicide risk screening during nursing triage using a standardized suicide screening tool. Suicide risk screening results, demographic variables, and medical history (as available) for patients with Sturge-Weber syndrome (N = 34; median age = 15.5; range = 8 to 47 years, 44% male) and other neurological conditions seen at the same institution (N = 369; median age = 14; range = 8 to 78 years, 66% male) were used for retrospective within- and between-group analysis. RESULTS In the combined sample of Sturge-Weber syndrome and neurologically involved patients, a positive suicide risk screen was related to Sturge-Weber syndrome diagnosis (P = 0.043); analysis by sex showed increased risk of Sturge-Weber syndrome diagnosis in males (P = 0.008), but not in females. Within the Sturge-Weber syndrome group, use of a selective serotonin reuptake inhibitor (P = 0.019) was related to a positive risk screen. CONCLUSION People with Sturge-Weber syndrome may be at greater risk of suicidal thoughts or behaviors than those with other neurological conditions. Further study of suicide risk in patients with Sturge-Weber syndrome is needed.
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Abstract
National Patient Safety Goal 15.01.01 requires all Joint Commission-accredited organizations to screen patients treated for behavioral health conditions for suicide risk. However, little is known about the ability of screening tools to identify suicide risk among youths with psychotic disorders. As part of this quality improvement initiative, youths in a pediatric emergency department with psychotic disorder diagnoses (N=87) were screened with the Ask Suicide-Screening Questions. Almost half (48%, N=42) screened positive. Most positive screens (62%, N=26) were not detected through treatment as usual, suggesting that systematic screening improves the detection of suicide risk among youths with psychotic disorders.
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Assessment of Selective and Universal Screening for Suicide Risk in a Pediatric Emergency Department. JAMA Netw Open 2019; 2:e1914070. [PMID: 31651971 PMCID: PMC6822088 DOI: 10.1001/jamanetworkopen.2019.14070] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 09/08/2019] [Indexed: 12/03/2022] Open
Abstract
Importance According to National Patient Safety Goal 15.01.01, all individuals being treated or evaluated for behavioral health conditions as their primary reason for care in hospitals and behavioral health care organizations accredited by The Joint Commission should be screened for suicide risk using a validated tool. Existing suicide risk screens have minimal or no high-quality evidence of association with future suicide-related outcomes. Objective To test the association between results of the Ask Suicide-Screening Questions (ASQ) instrument in a pediatric emergency department (ED), implemented through selective and universal screening approaches, and subsequent suicide-related outcomes. Design, Setting, and Participants In this retrospective cohort study at an urban pediatric ED in the United States, the ASQ was administered to youths aged 8 to 18 years with behavioral and psychiatric presenting problems from March 18, 2013, to December 31, 2016 (selective condition), and then to youths aged 10 to 18 years with medical presenting problems (in addition to those aged 8-18 years with behavioral and psychiatric presenting problems) from January 1, 2017, to December 31, 2018 (universal condition). Exposure Positive ASQ screen at baseline ED visit. Main Outcomes and Measures The main outcomes were subsequent ED visits with suicide-related presenting problems (ie, ideation or attempts) based on electronic health records and death by suicide identified through state medical examiner records. Association with suicide-related outcomes was calculated over the entire study period using survival analyses and at 3-month follow-up for both conditions using relative risk. Results The complete sample was 15 003 youths (7044 [47.0%] male; 10 209 [68.0%] black; mean [SD] age, 14.5 [3.1] years at baseline). The follow-up for the selective condition was a mean (SD) of 1133.7 (433.3) days; for the universal condition, it was 366.2 (209.2) days. In the selective condition, there were 275 suicide-related ED visits and 3 deaths by suicide. In the universal condition, there were 118 suicide-related ED visits and no deaths during the follow-up period. Adjusting for demographic characteristics and baseline presenting problem, positive ASQ screens were associated with greater risk of suicide-related outcomes among both the universal sample (hazard ratio, 6.8 [95% CI, 4.2-11.1]) and the selective sample (hazard ratio, 4.8 [95% CI, 3.5-6.5]). Conclusions and Relevance Positive results of both selective and universal screening for suicide risk in pediatric EDs appear to be associated with subsequent suicidal behavior. Screening may be a particularly effective way to detect suicide risk among those who did not present with ideation or attempt. Future studies should examine the impact of screening in combination with other policies and procedures aimed at reducing suicide risk.
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Desensitization of CXC chemokine receptor 4, mediated by IL-16/CD4, is independent of p56lck enzymatic activity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:6356-63. [PMID: 11086073 DOI: 10.4049/jimmunol.165.11.6356] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CCR5 and CXC chemokine receptor 4 (CXCR4) are coreceptors for CD4 as defined by HIV-1 glycoprotein (gp) 120 binding. Pretreatment of T cells with gp120 results in modulation of both CCR5 and CXCR4 responsiveness, which is dependent upon p56(lck) enzymatic activity. The recent findings that pretreatment of T cells with a natural CD4 ligand, IL-16, could alter cellular responsiveness to macrophage-inflammatory protein-1ss (MIP-1ss) stimulation, prompted us to investigate whether IL-16 could also alter CXCR4 signaling. These studies demonstrate that IL-16/CD4 signaling in T lymphocytes also results in loss of stromal derived factor-1alpha (SDF-1alpha)/CXCR4-induced chemotaxis; however, unlike MIP-1ss/CCR5, the effects were not reciprocal. There was no effect on eotaxin/CCR3-induced chemotaxis. Desensitization of CXCR4 by IL-16 required at least 10-15 min pretreatment; no modulation of CXCR4 expression was observed, nor was SDF-1alpha binding altered. Using murine T cell hybridomas transfected to express native or mutated forms of CD4, it was determined that IL-16/CD4 induces a p56(lck)-dependent inhibitory signal for CXCR4, which is independent of its tyrosine catalytic activity. By contrast, IL-16/CD4 desensitization of MIP-1ss/CCR5 responses requires p56(lck) enzymatic activity. IL-16/CD4 inhibition of SDF-1alpha/CXCR4 signals requires the presence of the Src homology 3 domain of p56(lck) and most likely involves activation of phosphatidylinositol-3 kinase. These studies indicate the mechanism of CXCR4 receptor desensitization induced by a natural ligand for CD4, IL-16, is distinct from the inhibitory effects induced by either gp120 or IL-16 on CCR5.
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Abstract
In this article, David Center and colleagues clarify the controversies that have emerged over the unique structure of interleukin 16 and its anti-HIV-1 activity. Interleukin 16 is a ligand for CD4, and this implies CD4 acts as a sentinel receptor that can switch CD4+ T cells between immune and inflammatory functions.
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Reciprocal desensitization of CCR5 and CD4 is mediated by IL-16 and macrophage-inflammatory protein-1 beta, respectively. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1999; 163:3123-30. [PMID: 10477578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
The ability of HIV-1 gp120 to inhibit chemokine signaling prompted us to determine whether signaling through CD4 by a natural ligand, IL-16, could alter cellular responsiveness to chemokine stimulation. These studies demonstrate that IL-16/CD4 signaling in T lymphocytes results in a selective loss of macrophage-inflammatory protein (MIP)-1 beta/CCR5-induced chemotaxis. There was no effect on monocyte chemoattractant protein-2/CCR1, -2, or -3-induced chemotaxis. Desensitization of CCR5 by IL-16 required at least 10 min of pretreatment; no modulation of CCR5 expression was observed, nor was MIP-1 beta binding to CCR5 altered. Using murine T cell hybridomas transfected to express native or mutated forms of CD4, it was determined that IL-16/CD4 induces a p56lck-dependent signal that results in desensitization of CCR5. The desensitization process is reciprocal and again selective, as prior CCR5 stimulation, but not CCR1, -2, or -3 stimulation, completely inhibits IL-16/CD4-induced T cell migration. Of interest, while p56lck enzymatic activity is not required for IL-16-induced migration, it was required for desensitization of CCR5. These studies indicate the existence of reciprocal receptor cross-desensitization between CD4 and CCR5 induced by two proinflammatory cytokines and suggest a selective relationship between the two receptors.
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Abstract
Human interleukin-16, previously known as lymphocyte chemoattractant factor, is a CD4+ T cell competence growth factor initially described as a chemotactic factor for CD4+ cells. The interaction between IL-16 and its receptor CD4 leads to an increase in intracytoplasmic calcium and inositol triphosphate. Because of the association of intracellular shifts in protein kinase C (PKC) enzyme activity with production of these secondary messengers and the participation of PKC in transducing certain receptor-mediated migratory signals, we investigated the role of PKC in the CD4-mediated migratory response by IL-16. Recombinant IL-16 induces rapid translocation of PKC from the cytosol to the membrane in three separate CD4+ cell types: normal blood T cells, SUPT1 cells, and THP1 cells. PKC inhibitors H7, calphostin C, chelerythrine, and bisindolylmaleimide completely block IL-16-induced lymphocyte migration as well as the motile response induced by HIV-1 gp120 and anti-CD4 antibodies. Taken together, these data suggest a role for PKC in CD4-mediated migratory responses.
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The CD4-associated tyrosine kinase p56lck is required for lymphocyte chemoattractant factor-induced T lymphocyte migration. J Biol Chem 1995; 270:17081-6. [PMID: 7615501 DOI: 10.1074/jbc.270.29.17081] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Lymphocyte chemoattractant factor (LCF) is a polypeptide cytokine which induces both cell motility and activation of T lymphocytes. These LCF-induced events demonstrate an absolute requirement for the cell surface expression of CD4. Because many CD4-mediated T lymphocyte activation events have been demonstrated to require the association of the src-related tyrosine kinase p56lck with the cytoplasmic domain of CD4, we examined the role of p56lck in LCF-induced lymphocyte migration in a murine T cell hybridoma line expressing transfected human CD4. LCF induces the catalytic activity of CD4 associated p56lck at chemoattractant concentrations of cytokine. Hybridoma cells that express CD4 with cytoplasmic point mutations which uncouple the CD4-lck association lack both lck enzymatic activity and chemotactic responses to LCF. The enzymatic activity of lck however does not appear to be required for CD4-mediated migratory signal. First, the protein tyrosine kinase inhibitor herbimycin A blocked LCF-induced p56lck activation but had no effect on the LCF-induced motile response. Second, T cell hybridomas expressing a chimeric receptor combining the extracellular domain of human CD4 and murine p56lck which lacked the kinase domain had a normal LCF-induced motile response. We conclude from these observations that CD4-lck coupling is essential for LCF-induced T lymphocyte migration but the motile response is independent of the enzymatic activity of CD4-associated p56lck.
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Measurement of superoxide release in the phagovacuoles of immune complex-stimulated human neutrophils. J Immunol Methods 1990; 130:223-33. [PMID: 2165099 DOI: 10.1016/0022-1759(90)90052-w] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Immune complex stimulation of human neutrophils elicits, among other events, the formation of phagocytic vacuoles into which the products of the stimulus activated oxidative burst and degranulation are released. In order to monitor burst activity in the phagocytic vacuole, we have developed a fluorochrome-coupled derivative of this neutrophil agonist. The fluorochrome 2',7'-dichlorodihydrofluorescein (DCFH) (the nonfluorescent, reduced form of 2',7'-dichlorofluorescein (DCF] has been covalently linked to bovine serum albumin (BSA), which can be used to form an immune complex with anti-BSA immunoglobulin. The resultant complex is an effective agonist for stimulating all immune complex-mediated neutrophil responses, as compared to nonderivatized controls. Upon exposure to hydrogen peroxide the stimulus-linked probe is converted to its oxidized, fully fluorescent form, the fluorescence of which is linearly related to the extent of probe oxidation. Using flow cytometry, we have demonstrated that the probe-stimulus complex is capable of monitoring the kinetics of the production of activated oxygen species by the membrane bound NADPH-oxidase enzyme, presumably within the phagocytic vacuoles of immune complex-activated neutrophils. We have found that the immune complex-mediated activation of the oxidative burst within the phagocytic compartment is preceded by a lag of approximately 30 s followed by a large sustained release of superoxide dependent hydrogen peroxide. Neutrophils from patients with chronic granulomatous disease, however, demonstrated no sustained increase in probe fluorescence, a finding consistent with the lack of oxidative burst activity in these cells. The DCFH-immune complex conjugate therefore provides an effective probe for monitoring the kinetics of the localized release of oxidative products within the forming phagocytic vacuoles of activated neutrophils, and may be used to further examine both the activation and activity of human neutrophils in response to 'physiologic' host defense agonists such as immune complexes.
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Letter: Self-audit of a general practice. S Afr Med J 1975; 49:1120. [PMID: 1173949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Management and Rehabilitation of Naval Battle Casualty Amputees. Ann Surg 1946; 124:1047-54. [PMID: 17858894 PMCID: PMC1803224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
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