The Influence of Social Media Interactions and Behaviors on Depressive Symptoms Among Sexual and Gender Minority Young Adults in the United States: Protocol for a Mixed Methods Longitudinal Study

BACKGROUND

Sexual and gender minority (SGM; ie, lesbian, gay, bisexual, transgender, and otherwise queer) young adults experience disparities in depression and other internalizing psychopathology. Although social media use is widespread and SGM people have more social media accounts and are more socially active on them than non-SGM individuals, few studies have examined the impact of social media on depression in this group.

OBJECTIVE

The PRIDE iM study will be the first longitudinal, mixed methods research conducted to determine the impact of social media interactions and behaviors as pathways to depressive symptoms among SGM young adults living in the United States.

METHODS

PRIDE iM uses a bookends variation of the longitudinal sequential mixed methods design. Participants will be recruited nationally from social media. First, between July 2019 and February 2020, we conducted a qualitative phase (T1) comprising web-based individual interviews (N=58) to inform the building and content of the quantitative survey. Second, from February 2022 to September 2022, we will conduct a series of web-based surveys (N=1000 at baseline) with 4 data points (T2-T5), each one collected every 6 to 8 weeks. Third, from October 2022 to December 2022, we will conduct a second qualitative phase (T6) of web-based interviews using outcome trajectories found in the longitudinal survey analyses to purposively sample survey participants and conduct web-based interviews to contextualize and explain survey findings. Qualitative data from T1 and T6 will be analyzed using a reflexive thematic analysis approach. As we sought to capture change over time in the association between the main predictors (ie, social media interactions and behaviors) and depressive symptoms, we propose analyzing T2 to T5 data using latent growth models with a structural equation modeling framework. Data integration at the method, interpretation, and reporting levels will be achieved through building and connecting and the use of a staged approach and joint displays, respectively. At all stages, we will assess the fit of data integration as recommended by the principles of best practice for mixed methods research in psychology.

RESULTS

Data collection will be completed by December 2022. Qualitative data analyses will be completed by March 2023, and quantitative analyses of the primary outcome of interest will be completed by June 2023.

CONCLUSIONS

PRIDE iM will confirm, reject, or uncover the presence of potential relationships between social media interactions and behaviors and depressive symptoms among SGM people. This study represents fundamental groundwork to develop social media-based interventions that target modifiable interactions and behaviors that are most likely to influence mental health outcomes, thus seizing the opportunity to merge the popularity of this medium among SGM people with evidence-based approaches.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/43627.

Opioid use as a proximal risk factor for suicidal behavior in young adults

INTRODUCTION

There is a concomitant rise in suicide rates with the prevalence of opioids involved in overdose deaths, especially among adolescents and young adults. However, there are limited studies on whether opioid use prospectively predicts suicidal behavior in youth.

METHODS

Our sample included 183 psychiatric patients (18-30 years) admitted for a suicide attempt (SA), have current suicidal ideation (SI), and psychiatric controls without ideation or attempt (PC). Suicidal behavior was assessed using the Columbia Suicide Severity Rating Scale. We also recruited a healthy control group (HC; n = 40). Patients and controls were followed over a year. ANOVA, regression, and cox regression were used.

RESULTS

Suicide attempt (β = 0.87, CI [0.1-1.6], p = 0.02) and SI [(β = 0.75, CI [0.03-1.5], p = 0.04) were significantly more likely than HCs to have used opioids in the past year at baseline. Opioid use was associated with increased anxiety symptoms (β = 0.75, CI [0.001-1.5], p = 0.05), PTSD symptoms (β = 3.90, CI [1.1-6.7], p = 0.01), and aggression (β = 0.02, CI [0.01-0.04], p = 0.02). Opioid use in the month prior to hospitalization predicted SA at 6 months (OR = 1.87, CI [1.06-3.31], p = 0.032).

CONCLUSIONS

Opioid use is a proximal predictor for SA. These findings may help clinicians better identify patients at risk for suicidal behavior, allowing for more personalized treatment approaches.

The psychiatric sequelae of the COVID-19 pandemic in adolescents, adults, and health care workers

BACKGROUND

The COVID-19 pandemic is the most serious global public health crisis since the 1918 influenza pandemic. This study is the first to assess its mental health impact across the lifespan in the United States in adolescents, adults, and health care workers.

METHODS

We recruited 4909 participants through an online survey advertising on Facebook and Instagram to assess exposure to COVID-19 and psychiatric symptoms from April 27 to July 13. We also recruited through the University of Pittsburgh, University of Pittsburgh Medical Center, and other health care systems around Pittsburgh. The primary outcomes were clinically significant depression, anxiety, and posttraumatic stress disorder (PTSD) symptoms, suicidal ideation or behavior, and grief reactions since COVID-19.

RESULTS

Adolescents were significantly more likely to report moderate to severe symptoms of depression (55% vs. 29%; χ²  = 122, df = 1; p < .001), anxiety (48% vs. 29%; χ²  = 73; df = 1; p < .001), PTSD (45% vs. 33%; χ²  = 12; df = 1; p < .001), suicidal ideation or behavior (38% vs. 16%; χ²  = 117; df = 1; p < .001), and sleep problems (69% vs. 57%; χ²  = 26; df = 1; p < .001) compared to adults. The rates of intense grief reactions among those who lost someone to COVID-19 was 55%. Loneliness was the most common predictor across outcomes and higher number of hours spent on social media and exposure to media about COVID-19 predicted depression symptoms and suicidal ideation or behavior in adolescents.

CONCLUSIONS

The COVID-19 pandemic is associated with increased rates of clinically significant psychiatric symptoms. Loneliness could put individuals at increased risk for the onset of psychiatric disorders.

Rationale and design of CAPITA: a RCT of 13-valent conjugated pneumococcal vaccine efficacy among older adults

The burden of community-acquired pneumonia (CAP) among the elderly is high and has increased over the last decades. Streptococcus pneumoniae is the most common cause of CAP and in 10% the infection may be fatal. Although the 23-valent polysaccharide pneumococcal vaccine (23vPS) is considered effective in the prevention of invasive pneumococcal disease in the elderly population, the evidence is mainly from nonrandomised observational studies and effects on the occurrence of pneumonia have not been demonstrated. Conjugated pneumococcal vaccines which also stimulate T-cell dependent immune responses induced antibody responses in elderly persons which are similar to those induced by a primary series of 7-valent conjugated pneumococcal vaccine (7vPnC) in infants, and the response appeared similar or superior for all vaccine serotypes to that induced by 23vPS. The primary objective of the planned trial entitled CAPITA (Community Acquired Pneumonia Immunization Trial in Adults) is to establish the efficacy of a 13-valent PnC vaccine in the prevention of a first episode of vaccine-serotype specific pneumococcal CAP in 85,000 community-dwelling adult persons aged 65 years and older. This is a parallel group, randomised, placebo-controlled trial, with a 1:1 random allocation to vaccine or placebo vaccine. The occurrence of the primary outcome of vaccine-serotype specific (VT)-CAP will be established in hospitals on the basis of three sets of criteria: (1) a clinical definition of CAP; (2) independent interpretation of chest radiograph consistent with pneumonia: and (3) determination of S. pneumonia serotype. the trial will be critical to determine the position of conjugate pneumococcal vaccines in the prevention of pneumococcal disease.

Prevalence of weight gain in patients with better renal transplant function

AIMS

This study investigates the association between renal function and change in weight after kidney transplantation.

METHODS

Retrospective analyses of 165 transplant patients on maintenance steroids who were followed-up for 6.2 +/- 2.4 years.

RESULTS

101 males and 64 females participated in the study. Results are expressed as mean +/- SD. At the first post-transplant outpatient visit (time 0), BMI was 25.3 +/- 4.8 kg/m2. It increased significantly by 7.7 +/- 10.8% and 10.9 +/- 12.6% at 1 and 5 years. 18 and 29% of patients had a BMI > 30 kg/m2 at times 0 and 5 years, respectively. Thereafter, diminishing glomerular filtration rate (GFR) was associated with the loss of the excess weight. Multivariate analysis showed that GFR, but not age, race, sex, source of graft, number of HLA mismatches or length of dialysis was significant to post-transplant weight gain. 38 patients gained weight > 1 SD above the mean of the population and were designated the high weight gain (HWG) group. 41 patients gained weight < the mean - 1 SD of the population and were designated the low weight gain (LWG) group. GFR in the high and low weight gain groups at time 0 was 71.8 +/- 20.3 ml/min/1.73 m2 and 66.4 +/- 23.1 ml/min/1.73 m2, respectively (p = NS), as compared to 77.4 +/- 23.3 ml/min/1.73 m2 and 61.5 +/- 24.5 ml/min/ 1.73 m2 at 6 months, respectively (p < 0.01) and continued to be significant thereafter (72.7 +/- 17.2 ml/min/1.73 m2 and 58.9 +/- 19.8 ml/min/1.73 m2, p < 0.05 at 6 years).

CONCLUSIONS

Patients with relatively better renal transplant function gained more weight, suggesting a pivotal role of improved appetite on weight gain post transplantation. Most of the weight gain occurred during the first year.

Emerging viral pathogens in long-term expatriates (II): Dengue virus

Dengue virus infections have been well known for many years; still dengue virus is regarded as an 'emerging' pathogen, as the disease profile is changing. Its geographical range and overall incidence, and the incidence of the associated complications, dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS), are on the increase. Modern-day travel and increasing urbanization seem to be the main contributing factors. In order to estimate the risk of infection during long-term stays in dengue-endemic countries, we tested sera obtained from 323 development aid workers and their family members who had spent on average 9.8 years in dengue-endemic regions for the presence of dengue virus antibodies. Dengue virus antibody screening was done by a commercially available immunofluorescence test (IF). Reactive samples were re-tested by an in-house IF and also tested for cross-reactivity to yellow fever virus using yellow fever IF and neutralization test (NT). Evaluation of the results revealed that the screening test has a specificity of at least 63.2%. In 12 of 19 initially positive cases crossreacting antibodies against yellow fever virus could be ruled out. Three cases remained indeterminable, whereas four of the reactive and 10 (out of 12) of the borderline reactive cases showed crossreactivity with yellow fever virus, probably due to previous vaccination. We found seroprevalence rates of 4.3% with no significant differences related to gender or area of upbringing. Seroprevalence rates were evaluated according to region of suspected or confirmed infection. In two cases the dengue infection had taken a classical clinical course; in another three cases an extraordinary febrile illness was reported in the history. None of the other seropositive individuals had a history of an illness possibly attributable to dengue virus infection. Our results show that there definitely is a risk for long-term expatriates to acquire (mostly non- or oligo-symptomatic) dengue infection, which might be important especially in the light of the supposed aetiology of DHF or DSS as a secondary infection with another dengue virus serotype.

Emerging viral pathogens in long-term expatriates (I): Hepatitis E virus

Hepatitis E virus (HEV) is one of the so-called 'emerging' viral pathogens, whose role is increasingly being recognized. To estimate the risk of HEV infection during long-term stays in HEV-endemic countries, 500 serum samples obtained from development aid workers and their family members who had spent on average 9 years in HEV-endemic regions were tested for antibodies against HEV by ELISA and Immunoblot. We found seroprevalence rates of 5-6% with no significant differences related to gender or area of upbringing (raised in an HEV-endemic vs. nonendemic region). Seroprevalence rates did not increase with increasing number of stays or number of expatriate years. None of 77 children and adolescents tested was positive for anti-HEV. The Indian subcontinent showed the highest seropositive rate with 10%. In subjects returning from West and Central Africa, East Africa, South-east Asia and Latin America seroprevalence rates were around 7%. We found a comparatively low seroprevalence rate of 2.1% for the Arab countries and the Middle East. Our results show that there definitely is a risk for long-term expatriates to acquire HEV infection; however, in most of our cases infection seems to have been non- or oligo-symptomatic.

Dual oncostatin M (OSM) receptors. Cloning and characterization of an alternative signaling subunit conferring OSM-specific receptor activation

Oncostatin M (OSM) is a cytokine whose structural and functional features are similar to other members of the interleukin (IL)-6 family of cytokines (IL-6, IL-11, leukemia inhibitory factor (LIF), granulocyte colonystimulating factor, ciliary neurotrophic factor, and cardiotrophin-1), many of which utilize gp130 as a common receptor subunit. A biologically active OSM receptor has been previously described that consists of a heterodimer of leukemia inhibitory factor receptor (LIFR) and gp130. This LIFR.gp130 complex is also a functional receptor for LIF. We have cloned and characterized an alternative subunit (OSMRbeta) for an OSM receptor complex (a heterodimer of gp130 and OSMRbeta) that is activated by OSM but not by LIF. The signaling capability of specific receptor subunit combinations was analyzed by independent assays measuring cell proliferation or induction of acute phase protein synthesis. Our results demonstrate that both LIF and OSM cause tyrosine phosphorylation and activation of the gp130.LIFR combination, but the gp130.OSMRbeta complex is activated by OSM only. OSM-induced cellular responses, initiated through low affinity binding to gp130, are mediated by two heterodimeric receptor complexes that utilize alternative signal transducing subunits that confer different cytokine specificities to the receptor complex.

Evaluation of hemoperitoneum using a single- vs multiple-view ultrasonographic examination

OBJECTIVE

To compare the sensitivities, specificities, and accuracies between a single-view ultrasonography (US) technique and a multiple-view technique for identifying hemoperitoneum in multiple-trauma patients.

METHODS

Data from a prior prospective study of US for trauma diagnosis at a level I trauma center were retrospectively analyzed. A convenience sample of adult patients (> or = 18 years of age) who had presented with major blunt or penetrating torso trauma and had undergone rapid trauma US examinations to detect hemoperitoneum were reviewed. The US interpretations by emergency physicians had been recorded prior to obtaining other diagnostic tests. Five views were evaluated, including the right intercostal oblique view examining Morison's pouch. Evidence of free intraperitoneal fluid by exploratory laparotomy, CT, or diagnostic peritoneal lavage (DPL) was used as the criterion standard.

RESULTS

Of the 245 patients entered into the study, 37 had free intraperitoneal fluid, confirmed by CT, DPL, or exploratory laparotomy. With the multiple-view technique, US was 87% (95% CI = 71%, 96%) sensitive, 100% (95% CI = 97%, 100%) specific, and 98% (95% CI = 95%, 100%) accurate. The single-view technique, evaluating only Morison's pouch, was 51% (95% CI = 34%, 68%) sensitive, 100% (95% CI = 98%, 100%) specific, and 93% (95% CI = 89%, 96%) accurate.

CONCLUSIONS

An initial trauma US examination using a multiple-view technique is more sensitive than that using a single-view technique for detecting hemoperitoneum in trauma patients.

Targeted disruption of the low-affinity leukemia inhibitory factor receptor gene causes placental, skeletal, neural and metabolic defects and results in perinatal death

The low-affinity receptor for leukemia inhibitory factor (LIFR) interacts with gp130 to induce an intracellular signal cascade. The LIFR-gp130 heterodimer is implicated in the function of diverse systems. Normal placentation is disrupted in LIFR mutant animals, which leads to poor intrauterine nutrition but allows fetuses to continue to term. Fetal bone volume is reduced greater than three-fold and the number of osteoclasts is increased six-fold, resulting in severe osteopenia of perinatal bone. Astrocyte numbers are reduced in the spinal cord and brain stem. Late gestation fetal livers contain relatively high stores of glycogen, indicating a metabolic disorder. Hematologic and primordial germ cell compartments appear normal. Pleiotropic defects in the mutant animals preclude survival beyond the day of birth.

Oncostatin M and leukemia inhibitory factor trigger overlapping and different signals through partially shared receptor complexes

Leukemia inhibitory factor (LIF) and oncostatin M (OSM) both bind to the same receptor with high affinity and thus mediate an overlapping spectrum of biological activities, the signal transduction mechanisms for which are unclear. We show that mitogen-activated protein kinases are involved in both the LIF and OSM signal transduction pathways. However, we found that OSM is a much more potent inducer of both mitogen-activated protein kinase activity and biological response, both of which correlate with the expression of a second OSM receptor that does not bind LIF. In addition, different patterns of tyrosine-phosphorylated proteins were stimulated by OSM and LIF. We therefore suggest that the two receptors for OSM can be coupled to different signal transduction events.

Proliferative responses and binding properties of hematopoietic cells transfected with low-affinity receptors for leukemia inhibitory factor, oncostatin M, and ciliary neurotrophic factor

Specific low-affinity receptors for leukemia inhibitory factor (LIF), oncostatin M (OSM; gp130), and ciliary neurotrophic factor (CNTF; receptor alpha, CNTFR alpha) may be utilized in various combinations to generate high-affinity binding sites and signal transduction. We have tested the ability of combinations of these receptors to transduce a proliferative signal in BAF-B03 cells. Coexpression of the LIF receptor and gp130 in these cells conferred high-affinity LIF and OSM binding and responsiveness to LIF and OSM. These cells also responded to CNTF in the absence of detectable binding. The further addition of CNTFR alpha conferred high-affinity CNTF binding and enhanced responsiveness to CNTF but did not modify responses to LIF or OSM. Coexpression of LIF receptor and CNTFR alpha resulted in a nonfunctional high-affinity binding site. These data are consistent with a role for the CNTFR alpha in enhancing CNTF action but the CNTFR alpha is not absolutely required for CNTF action and suggest a wider range of targets for CNTF.

Evidence that MAP (mitogen-activated protein) kinase activation may be a necessary but not sufficient signal for a restricted subset of responses in IL-1-treated epidermoid cells

We have investigated the activation of mitogen-activated protein kinase (MAP-kinase) in KB human epidermoid carcinoma cells treated with interleukin 1 (IL-1). MAP-kinase activity was transient; the time required for activity to reach a maximal level was dependent upon the dose of IL-1, ranging from 15 minutes to 45 minutes. The level of kinase induction correlated well with dose-response curves for two characteristic IL-1-induced responses, PGE2 and IL-6 production. MAP-kinase activity returned to basal levels within 2 hours regardless of the amount of IL-1 added to the system. Exposure of KB cells to free IL-1 was accordingly restricted to periods of 2 hours or less, by replacing IL-1 with an excess of IL-1 receptor antagonist. Even after 2 hours exposure, the ability of IL-1 to induce IL-6 or PGE2 was still IL-1ra-inhibitable by more than 80%, suggesting that events downstream of, or parallel to MAP-kinase activation, requiring the continual formation of new IL-1 receptor complexes, are needed to fully elicit these responses. Two general serine/threonine kinase inhibitors, K252a and quercetin, were found to strongly inhibit MAP kinase in vivo with ED50s of c. 100 nM and 30 microM, respectively. At these concentrations, both compounds effectively inhibited IL-1-driven PGE2 and IL-6 induction without affecting general protein synthesis or secretion. Other non-selective kinase inhibitors had less effect on MAP-kinase activation or IL-1-induced biological responses. The transient activation of MAP-kinase induction correlated strikingly with activation of the transcription factor NF-kappa B. IL-1-induced NF-kappa B activation was, however, relatively insensitive to inhibition by K252a or quercetin. We suggest that MAP-kinase is likely to be a necessary, but not sufficient, intermediate in some (IL-6, PGE2 induction) but not all (NF-kappa B activation) IL-1 responses in these cells.

Inhibition of tumor necrosis factor (TNF)-mediated NF-kappa B activation by selective blockade of the human 55-kDa TNF receptor

The numerous biologic activities of TNF appear mediated by two types of specific cell surface receptors of 55 to 60 kDa (TR55) and 75 to 80 kDa (TR75) molecular mass, respectively. The role of TR55 in the activation of the nuclear transcription factor kappa B (NF-kappa B) was investigated using an antagonistic, mAb, H398, specific for the human TR55. The human leukemic T cell line, Jurkat, which expresses both types of receptors at comparable levels, was used to test for NF-kappa B activation by electrophoretic mobility shift assays using as a probe an oligonucleotide encompassing the two tandemly arranged kappa B sites of the HIV-1 LTR enhancer. mAb H398 is shown to efficiently block not only TNF- but also lymphotoxin-mediated activation of NF-kappa B. Furthermore mAb H398 also impeded TNF- or lymphotoxin-mediated activation of chloramphenicol acetyl transferase gene expression from the HIV-1-LTR as determined by transient transfection assays. These findings indicate that both, induction of NF-kappa B binding to DNA, and transcriptional activity can be efficiently inhibited by selective blockade of TR55. Finally it is shown, that human TR55 confers NF-kappa B inducibility when expressed in the mouse pre-B cell line 70Z/3, which does not respond to TNF in its parental state. Together, the results of this study indicate that TR55 is both necessary and sufficient for mediating TNF activation of NF-kappa B.

Inhibition of tumor necrosis factor (TNF)-mediated NF-kappa B activation by selective blockade of the human 55-kDa TNF receptor

The numerous biologic activities of TNF appear mediated by two types of specific cell surface receptors of 55 to 60 kDa (TR55) and 75 to 80 kDa (TR75) molecular mass, respectively. The role of TR55 in the activation of the nuclear transcription factor kappa B (NF-kappa B) was investigated using an antagonistic, mAb, H398, specific for the human TR55. The human leukemic T cell line, Jurkat, which expresses both types of receptors at comparable levels, was used to test for NF-kappa B activation by electrophoretic mobility shift assays using as a probe an oligonucleotide encompassing the two tandemly arranged kappa B sites of the HIV-1 LTR enhancer. mAb H398 is shown to efficiently block not only TNF- but also lymphotoxin-mediated activation of NF-kappa B. Furthermore mAb H398 also impeded TNF- or lymphotoxin-mediated activation of chloramphenicol acetyl transferase gene expression from the HIV-1-LTR as determined by transient transfection assays. These findings indicate that both, induction of NF-kappa B binding to DNA, and transcriptional activity can be efficiently inhibited by selective blockade of TR55. Finally it is shown, that human TR55 confers NF-kappa B inducibility when expressed in the mouse pre-B cell line 70Z/3, which does not respond to TNF in its parental state. Together, the results of this study indicate that TR55 is both necessary and sufficient for mediating TNF activation of NF-kappa B.

Identification of a 60-kD tumor necrosis factor (TNF) receptor as the major signal transducing component in TNF responses

We describe here a monoclonal antibody (H398) that immunoprecipitates a human 60-kD tumor necrosis factor (TNF) membrane receptor (p60) and competes with TNF binding to p60 but not to p85 TNF receptors. Despite partial inhibition of TNF binding capacity of cells coexpressing both TNF receptor molecules, H398 uniformly and completely inhibits very distinct TNF responses on a variety of cell lines. These data suggest a limited structural heterogeneity in those components actually contributing to TNF responsiveness and identify p60 as a common receptor molecule essential for TNF signal transduction. As H398 is a highly effective TNF antagonist in vitro, it might be useful as a therapeutic agent in the treatment of TNF-mediated acute toxicity.

Glycosylation of the human interferon-gamma receptor. N-linked carbohydrates contribute to structural heterogeneity and are required for ligand binding

The contribution of N-linked carbohydrates to human interferon-gamma receptor (hIFN-gamma-R) structure and function was investigated in four tumor cell lines of various tissue origin. Western and ligand blotting of native and deglycosylated, affinity-purified hIFN-gamma-R of the monocytic cell line U937 and the lymphoid cell line Raji revealed that the different sizes of hIFN-gamma-R from U937 (103 kDa) and Raji (90 kDa) cells are reduced upon either metabolic inhibition or enzymatic deglycosylation of N-linked carbohydrates to a common size of the receptor molecule with an apparent molecular mass of 73 kDa for both cell lines, indicating that heterogeneity in hIFN-gamma-R size is largely due to differential glycosylation. In all cell lines investigated, inhibition of N-linked glycosylation or modulation of carbohydrate processing did not prevent receptor transport to the cell membrane, but blocked hIFN-gamma binding capacity of membrane-expressed receptor molecules, as revealed by specific binding of hIFN-gamma-R-specific monoclonal antibody and specific binding of 125I-labeled hIFN-gamma. These data suggest that a lack of complex-type N-linked carbohydrates is associated with a complete loss of receptor function, i.e. high affinity binding capacity. Recovery of hIFN-gamma binding of deglycosylated receptors was achieved upon affinity purification and adsorption to nitrocellulose membranes, indicating that the carbohydrate side chains themselves do not directly contribute to the ligand binding epitope but seem to be essential for appropriate conformation of the receptor protein in the cell membrane.

Downregulation of tumor necrosis factor (TNF) sensitivity via modulation of TNF binding capacity by protein kinase C activators

The regulatory action of activators for protein kinase C on the specific binding capacity for recombinant human tumor necrosis factor alpha (TNF-alpha) was studied on various human cell lines. Phorbol myristate acetate (PMA) and oleyl acetyl glycerol (OAG) both are able to rapidly downregulate TNF-binding capacity of normal and malignant cells derived from various tissues. As PMA treatment did not enhance internalization of TNF-alpha-receptor complexes at 37 degrees C, and since OAG was able to downregulate TNF-binding capacity under conditions where internalization and shedding of receptor protein are prevented, we conclude that protein kinase C controls ligand affinity of the TNF-receptor protein, possibly via direct phosphorylation. Protein kinase C triggered downregulation of TNF-alpha-binding capacity concomitantly resulted in reduction of TNF-alpha sensitivity, as revealed from decreased cytotoxic action of TNF-alpha on L 929 cells and from inhibition of TNF-alpha-mediated enhancement of HLA class II antigen expression in Colo 205 cells. Restoration of TNF-binding capacity upon abrogation of protein kinase C stimulation leads to full recovery of TNF responsiveness, further supporting the close linkage of TNF-receptor expression and TNF sensitivity. These data suggest that regulation of TNF-binding capacity by protein kinase C is one of the cellular control mechanisms of TNF responsiveness.

Immunoregulatory activity of recombinant human tumor necrosis factor (TNF)-alpha: induction of TNF receptors on human T cells and TNF-alpha-mediated enhancement of T cell responses

The expression of specific tumor necrosis factor (TNF) membrane receptors and biological effects of recombinant TNF (rTNF)-alpha on normal human T lymphocytes were studied. Although resting T cells lacked specific binding capacity for rTNF-alpha, high affinity (Kd 70 pM) TNF receptors were de novo induced upon primary activation of T cells. Comparison of TNF receptor expression with that of high affinity interleukin 2 (IL-2) and interferon-gamma (IFN-gamma) receptors, respectively, revealed similarities to IL 2-receptor expression with respect to kinetics of induction. However, maximum expression of TNF receptors (approximately equal to 5000/cell at day 6) and subsequent decline occurred approximately 3 days after the peak of IL 2-receptor expression. In contrast, no change in the expression of IFN-gamma receptors (Kd 10 pM, 300 to 400 receptors/cell) was found in the course of T cell activation. On activated TNF receptor positive T cells, TNF-alpha exerted multiple stimulatory activities. Thus TNF increased the expression of HLA-DR antigens and high affinity IL 2 receptors. As a consequence, TNF-treated T cells showed an enhanced proliferative response to IL 2. Moreover, TNF-alpha was effective as a co-stimulator of IL 2-dependent IFN-gamma production. These data indicate that TNF-alpha may regulate growth and functional activities of normal T cells.

Immunoregulatory activity of recombinant human tumor necrosis factor (TNF)-alpha: induction of TNF receptors on human T cells and TNF-alpha-mediated enhancement of T cell responses

The expression of specific tumor necrosis factor (TNF) membrane receptors and biological effects of recombinant TNF (rTNF)-alpha on normal human T lymphocytes were studied. Although resting T cells lacked specific binding capacity for rTNF-alpha, high affinity (Kd 70 pM) TNF receptors were de novo induced upon primary activation of T cells. Comparison of TNF receptor expression with that of high affinity interleukin 2 (IL-2) and interferon-gamma (IFN-gamma) receptors, respectively, revealed similarities to IL 2-receptor expression with respect to kinetics of induction. However, maximum expression of TNF receptors (approximately equal to 5000/cell at day 6) and subsequent decline occurred approximately 3 days after the peak of IL 2-receptor expression. In contrast, no change in the expression of IFN-gamma receptors (Kd 10 pM, 300 to 400 receptors/cell) was found in the course of T cell activation. On activated TNF receptor positive T cells, TNF-alpha exerted multiple stimulatory activities. Thus TNF increased the expression of HLA-DR antigens and high affinity IL 2 receptors. As a consequence, TNF-treated T cells showed an enhanced proliferative response to IL 2. Moreover, TNF-alpha was effective as a co-stimulator of IL 2-dependent IFN-gamma production. These data indicate that TNF-alpha may regulate growth and functional activities of normal T cells.

Rapid modulation of tumor necrosis factor membrane receptors by activators of protein kinase C

Tumor necrosis factor membrane receptors are rapidly down-regulated upon treatment of activated T lymphocytes with various activators of protein kinase C. Loss of binding-capacity was half maximal after 2 min. incubation in 10 ng/ml of phorbol 12-myristate 13-acetate. A similar modulation could be induced with either the calcium ionophore A 23187 or the protein kinase C activator 1-oleyl-2-acetyl glycerol, whereas 1,2-diolein and dibutyryl cAMP were ineffective. Protein kinase C inhibitor H7 antagonizes the phorbol ester-induced TNF receptor modulation. These data suggest an important role of protein kinase C in the control of TNF responsiveness by regulation of TNF binding-capacity possibly via direct phosphorylation of specific receptor proteins.

The value of morphological prognostic criteria in the assessment of renal cell carcinoma

In this study, we examined some of the morphological values from the large number of prognostic parameters indicated in the literature by establishing survival statistics. Primary distant metastasis formation was confirmed to be a prognostically unfavorable factor. Regional metastasis formation takes an intermediate position between the primarily distantly metastasized and the primary non-metastasized renal cell carcinoma. In the primarily non-metastasized renal cell carcinoma, tumor invasion into the renal vein is associated with prognostic deterioration, obviously due to a linkage to other unfavorable tumor characteristics. The histological degree of malignancy as a single prognostic parameter seems to be of little informational value if no other tumor data are taken into consideration. The classification of renal tumors according to Robson proves to be of great clinical relevance, especially when it is combined with the histological degree of malignancy. The prognostic scheme by Hermanek 'combined staging and grading' must be recommended as the prognostic scheme of choice. Apart from special histological types of the renal cell carcinoma, such as the papillary or sarcomatous variant, and with reservation as to the tendency to unpredictable secondary metastasis formation that is peculiar to the renal cell carcinoma, a prediction of the prognosis according to the morphological criteria mentioned above is possible to a satisfactory degree within certain limits.

Surgery of the primary tumor of metastasizing renal carcinoma

40% or 116 of 350 patients with renal carcinoma had distant metastases at the time of hospital admission (M1, N0-4). Women fell ill less often than men did (3:7). 82 of 116 patients (71%) received nephrectomy primarily. Lethality within the first 30 days was 6%. Patients with nephrectomy survived longer than those without, women with nephrectomy survived longer than men. Patients with a grade II tumor survived longer than those with a grade III tumor. Palliative nephrectomy can therefore be recommended as treatment of choice, if the general condition of the patient allows it, the more so as there are no alternative ways of treatment.