Brief video training for suicide prevention in veterans: A randomized controlled trial of VA S.A.V.E

INTRODUCTION

VA S.A.V.E. (Signs; Ask; Validate; Encourage/Expedite) is a gatekeeper training developed by the Department of Veterans Affairs (VA) that teaches individuals to identify and assist veterans at risk for suicide. Although VA S.A.V.E. has been widely disseminated, rigorous evaluation is lacking.

METHODS

In a pilot randomized controlled trial of a brief, video-based version of VA S.A.V.E., individuals were recruited through Facebook, randomized to VA S.A.V.E. versus an attention control condition, and completed 6-month follow-up. A subgroup (n = 15) completed interviews. We used a mixed methods framework to integrate quantitative and qualitative findings.

RESULTS

Among 214 participants, 61% were spouses/partners of veterans and 77% had prior suicide exposure. Sixty-seven percent (n = 68) of VA S.A.V.E. participants watched the entire video, and satisfaction and usability were highly rated. At 6-month follow-up, compared to the control group, the VA S.A.V.E. group had a higher proportion of participants use each gatekeeper behavior (66.7%-84.9% vs. 44.4%-77.1%), and used significantly more total gatekeeper behaviors (2.3 ± 0.9 vs. 1.8 ± 1.0; p = 0.01). Interviews supported positive reactions, learning, and behavior change from VA S.A.V.E.

CONCLUSION

VA S.A.V.E. merits further investigation into its effectiveness as a brief, scalable gatekeeper training for suicide prevention in veterans.

Toxicity of Detergent-based Commercial Products on Cells of a Mouse Line in Suspension Culture as a Possible Screen for the Draize Rabbit Eye Irritation Test

Summary

The Draize rabbit eye irritation test has several disadvantages and inadequacies when used as an indicator for potential irritancy of detergent-based commercial products. As a possible in vitro screen, it was decided to use mouse LS cells cultured in suspension, taking 50% cell death (CD50) after exposure to the product for 4h as the endpoint. This figure for 11 formulations was compared with eye irritation data ranked using an arbitrary classification of mild, moderate and severe. All samples with a CD50 less than 0.5mg/ml were severe eye irritants, while most of those with a CD50 greater than 1.0mg/ml were mild irritants. Samples between these two cytotoxicity levels were, in general, moderately irritant to the rabbit eye.

It would appear that this in vitro test is a possible screen for the irritancy of detergent-based products.

Objective Versus Self-Reported Adherence to Airway Clearance Therapy in Cystic Fibrosis

BACKGROUND

Historically, studies of adherence to airway clearance therapy in cystic fibrosis (CF) have relied on self-reporting. We compared self-reported airway clearance therapy adherence to actual usage data from home high-frequency chest wall compressions (HFCWC) vests and identified factors associated with overestimation of adherence in self-reports.

METHODS

Pediatric patients who perform airway clearance therapy with a HFCWC vest were eligible to participate. Objective adherence data were obtained from the HFCWC device, which records cumulative utilization time. Two readings at least 5 weeks apart were collected. Objective adherence was recorded as a ratio of mean-to-prescribed daily use (%). Self-reported adherence data were collected with a caregiver survey at enrollment. Adherence rates were categorized as low (< 35% of prescribed), moderate (36-79% of prescribed), and high (≥ 80% of prescribed). An overestimation was present when self-reported adherence was at least one category higher than objective adherence.

RESULTS

In the final sample (N = 110), mean adherence by usage data was 61%. Only 35% of subjects (n = 38) were highly adherent, and 28% (n = 31) were low adherent. In contrast, 65% of subjects (n = 72) reported high adherence and only 8% (n = 9) reported low adherence (P < .001). Nearly half of self-reports (46%) overestimated adherence. In a multiple regression analysis, overestimation was associated with multiple airway clearance therapy locations (odds ratio 7.13, 95% CI 1.16-43.72, P = .034) and prescribed daily use ≥ 60 min (odds ratio 3.85, 95% CI 1.08-13.76, P < .038). Among subjects with prescribed daily airway clearance therapy ≥ 60 min, the odds of overestimating adherence increased 3-fold (odds ratio 3.04, 95% CI 1.17-7.87, P = .02) in a lower-income (< $50,000/y) environment.

CONCLUSIONS

Self-reports overestimated actual adherence to airway clearance therapy, and the overestimation increased with treatment occurring in multiple households and prescribed therapy duration. Among participants with prescribed airway clearance therapy ≥ 60 min, overestimation increased with lower income. Objective measures of adherence are needed, particularly for lower-income children and those receiving treatments in multiple locations.

Using Primo for undergraduate research: a usability study

Purpose

The purpose of this paper is to observe how undergraduate students approach open-ended searching for a research assignment, specifically as it affected their use of the discovery interface Primo.

Design/methodology/approach

In total, 30 undergraduate students were provided with a sample research assignment and instructed to find resources for it using web tools of their choice, followed by the Primo discovery tool. Students were observed for 30 minutes. A survey was provided at the end to solicit additional feedback. Sources students found were evaluated for relevance and utility.

Findings

Students expressed a high level of satisfaction with Primo despite some difficulty navigating through more complicated tasks. Despite their interest in the tool and previous exposure to it, it was usually not the first discovery tool students used when given the research assignment. Students approached the open-ended search environment much like they would with a commercial search engine.

Originality/value

This paper focused on an open-ended search environment as opposed to a known-item scenario in order to assess students’ preferences for web search tools and how a library discovery layer such as Primo was a part of that situation. Evaluation of the resources students found relevant were also analyzed to determine to what degree the students understood the level of quality they exhibited and from which tool they were obtained.

Adherence to airway clearance therapy in pediatric cystic fibrosis: Socioeconomic factors and respiratory outcomes

OBJECTIVES

The evidence linking socioeconomic status (SES) and adherence in cystic fibrosis (CF) is inconclusive and focused on medication uptake. We examined associations between SES, adherence to airway clearance therapy (ACT), and CF respiratory outcomes.

STUDY DESIGN

Socioeconomic, clinical, and adherence data of CF patients (N = 110) at a single CF Center were evaluated in this cross-sectional observational study. SES was operationalized as maternal and paternal education and household income. Adherence to ACT was measured with utilization data from the high-frequency chest wall oscillation (HFCWO) device over 4-6 weeks. Statistical modeling was used to test three hypotheses: (H1) Higher SES is associated with higher ACT adherence; (H2) Higher SES is associated with better respiratory outcomes; and (H3) ACT adherence mediates the relationship between SES and respiratory outcomes.

RESULTS

In multinomial logistic regression, maternal college education, annual income >$50,000, and more adults in the household were independently related to better adherence (P < 0.05). Paternal college education, income >$100,000, and lack of exposure to smoking were independently related to higher lung function (P < 0.05). Current adherence to ACT with HFCWO was not associated with lung function over 12 months.

CONCLUSIONS

SES is associated both with ACT adherence and respiratory outcomes in pediatric CF patients. However, the link between SES and respiratory outcomes in this study was not mediated by adherence to ACT with HFCWO. These data emphasize the importance of socioeconomic resources and household environment for CF health. Family socio-demographic profiles can help identify patients at increased risk for ACT nonadherence.

Multisystemic abscesses in African green monkeys (Chlorocebus aethiops) with invasive Klebsiella pneumoniae--identification of the hypermucoviscosity phenotype

Invasive Klebsiella pneumoniae is an emerging disease of humans characterized by abscesses in the liver or other sites involving bacteria with the unique hypermucoviscosity phenotype. Over several months, 7 African green monkeys in our research colony developed abscess formation in multiple locations and succumbed to disease. K. pneumoniae was identified by bacterial culture in 6 monkeys and immunohistochemistry in 1 additional monkey. All monkeys had been housed in, or had contact with monkeys housed in, 1 animal room in our facility. All affected monkeys had 1 or more abscesses, most notably in the abdomen, but also affecting the lungs, cerebellum, and skin. Abdominal abscesses and associated adhesions entrapped loops of bowel, forming palpable masses. Abdominal masses were located at the root of the mesentery, the ileocecocolic junction, or the pelvic inlet. In 1 case, culture, serotyping, and polymerase chain reaction (PCR) analysis of the bacterial isolate identified K. pneumoniae expressing the hypermucoviscosity phenotype and capsular serotype K2 and determined that the K. pneumonia was genetically rmpA(+)/magA(-).

Planning of suicide attempts among depressed inpatients ages 50 and over

BACKGROUND

Suicidal behavior is heterogeneous; suicide attempts can be impulsive (lower planned) or reflect forethought and preparation (higher planned). Lower planned and higher planned attempts may have different correlates that require different prevention strategies. Based on a model of suicide planning relevant to middle-aged and older adults, we tested the following hypotheses: physical illness burden, decreased functional capacity, hopelessness, and living alone are associated with suicide attempts that are more extensively planned; lower cognitive functioning is associated with suicide attempts that are more impulsive.

METHODS

Subjects were 117 inpatients ages 50 and over diagnosed with major depression based on semi-structured clinical research interviews, the medical record, plus other records when available. All subjects had attempted suicide within 1 month of admission. The degree of planning prior to the suicide attempt was quantified using Beck's Suicide Intent Scale. Multivariate linear regression analysis identified correlates of planning.

RESULTS

As hypothesized, lower cognitive functioning was associated with lower levels of planning. Contrary to the hypothesis, impaired physical self-care was associated with lower (not higher) planning. Results pertaining to living alone were equivocal.

LIMITATIONS

The study was limited by the cross-sectional research design and unclear generalizability to completed suicide or to racial/ethnic minorities.

CONCLUSIONS

Depressed patients with lower cognitive functioning and impairments in physical self-care may be especially vulnerable to impulsive suicidal behavior. The potential role of living alone in higher planned suicidal acts requires further investigation.

Radiation-induced carcinogenesis: studies using human epithelial cell lines

It has proved difficult to develop suitable models to study radiation-induced carcinogenesis by using human epithelial cells. However, immortalised human epithelial cell lines have proved useful. Unirradiated cells from the human keratinocyte cell line (HPV-G) and the human embryonic lung cell line (L132) were found to be tumourigenic in T-cell-deficient mice; thus, they are not suitable for transformation studies. Human urothelial cell lines (SV-HUC-1, NT11, BC16) and the human thyroid epithelial cell line (HTori-3) were nontumourigenic. The urothelial cell lines were refractory to radiation-induced carcinogenesis, and only one small tumour was observed in 57 mice that received irradiated cells. Whereas tumours were not produced following irradiation of these urothelial cells, changes in anchorage-independent growth were observed after a single dose of 8 Gy gamma-irradiation but not after 2 or 4 Gy. Irradiation of the human thyroid epithelial cell line (HTori-3) in vitro resulted in tumour formation. Passaging of the cells in vitro before injection did not seem to be critical. Some of the cell lines derived from the primary thyroid tumours exhibited p53 mutations in exons 5, 6, 7, and 8, as detected by single-stranded conformational polymorphism (SSCP) analysis. Thus, the human thyroid epithelial cell line (HTori-3) looks promising as a model for investigating the molecular events in radiation-induced carcinogenesis.

The design, construction and calibration of a carefully controlled source for exposure of mammalian cells to extremely low-frequency electromagnetic fields

Despite some epidemiological evidence for an association between increased risk of cancer and exposure to electromagnetic fields (EMFs), cancer causation by such exposure remains unproven. Furthermore, for reasons such as biological unresponsiveness of the chosen system, poor equipment design and experimental confounders, no reproducible effects on animals or mammalian cells in culture have been demonstrated following exposure to power frequency EMFs at levels normally encountered in residential settings (<10 to 1000 microT). The apparatus described here, designed specifically to perform large, well-controlled cell biology experiments, reduces extraneous variables to the absolute minimum, so that small effects cannot be ascribed to some cause unrelated to the experimental protocol. Our novel apparatus consists of two identical solenoids which, in use, only differ by whether the field-producing current is flowing or not; they do not influence one another in any way. They are supplied with conditioned air from a common tissue culture incubator, are completely screened from environmental a.c. fields with Mumetal shielding and can be operated under normal laboratory conditions. Furthermore, the arrangement is such that the investigator is unaware whether cells have, or have not, been exposed until after the results have been evaluated. We report the design, construction, calibration and potential uses of this source.

The extravesicular domain of synaptotagmin-1 is released with the latent fibroblast growth factor-1 homodimer in response to heat shock

The heparin-binding fibroblast growth factor (FGF) prototypes lack a classical signal sequence, yet their presence is required in the extracellular compartment for the activation of cell-surface receptor-dependent signaling. Early studies with FGF-1 demonstrated its presence in bovine brain as a novel high molecular weight complex, and subsequent studies identified a second heparin-binding protein that co-purified with FGF-1. Polypeptide sequence analysis revealed that this heparin-binding protein corresponded to the extravesicular domain of bovine synaptotagmin (Syn)-1, a transmembrane component of synaptic vesicles involved in the regulation of organelle traffic. Since FGF-1 is released in response to heat shock as a mitogenically inactive Cys-30 homodimer, we sought to determine whether this heparin-binding protein was involved in the release of FGF-1. We report that a proteolytic fragment of the extravesicular domain of Syn-1 is associated with FGF-1 in the extracellular compartment of FGF-1-transfected NIH 3T3 cells following temperature stress. By using heparin-Sepharose affinity to discriminate between the monomer and homodimer forms of FGF-1 and resolution by conventional and limited denaturant gel shift immunoblot analysis, it was possible to identify FGF-1 and Syn-1 as potential components of a denaturant- and reducing agent-sensitive extracellular complex. It was also possible to demonstrate that the expression of an antisense-Syn-1 gene represses the release of FGF-1 in response to heat shock. These data indicate that FGF-1 may be able to utilize the cytosolic face of conventional exocytotic vesicles to traffic to the inner surface of the plasma membrane where it may gain access to the extracellular compartment as a complex with Syn-1.

Synaptotagmin-1 is required for fibroblast growth factor-1 release

By using p65 synaptotagmin-1 and fibroblast growth factor (FGF)-1:beta-galactosidase (beta-gal) NIH 3T3 cell co-transfectants, we demonstrate that a proteolytic fragment consisting of the extravesicular domain of synaptotagmin-1 is released into the extracellular compartment in response to temperature stress with similar kinetics and pharmacological properties as FGF-1:beta-gal. Using a deletion mutant that lacks 95 amino acids from the extravesicular domain of synaptotagmin-1, neither synaptotagmin-1 nor FGF-1:beta-gal are able to access the stress-induced release pathway. Furthermore, the p40 extravesicular fragment of synaptotagmin-1 is constitutively released in p40 synaptotagmin-1 NIH 3T3 cell transfectants, and this release is potentiated when the cells are subjected to temperature stress. These data demonstrate that the p40 fragment derived from synaptotagmin-1 is able to utilize the FGF-1 non-classical exocytotic pathway and that the release of FGF-1 is dependent on synaptotagmin-1.

Platinum catalysts for the high-yield oxidation of methane to a methanol derivative

Platinum catalysts are reported for the direct, low-temperature, oxidative conversion of methane to a methanol derivative at greater than 70 percent one-pass yield based on methane. The catalysts are platinum complexes derived from the bidiazine ligand family that are stable, active, and selective for the oxidation of a carbon-hydrogen bond of methane to produce methyl esters. Mechanistic studies show that platinum(II) is the most active oxidation state of platinum for reaction with methane, and are consistent with reaction proceeding through carbon-hydrogen bond activation of methane to generate a platinum-methyl intermediate that is oxidized to generate the methyl ester product.

Incision and drainage of cutaneous abscesses is not associated with bacteremia in afebrile adults

STUDY OBJECTIVE

To determine the prevalence of bacteremia associated with incision and drainage (I&D) of cutaneous abscesses in afebrile adult emergency department patients. Such information has implications for the ED management of immunocompromised patients, patients with history of endocarditis, and patients with prosthetic appliances such as heart valves and artificial joints.

METHODS

We conducted a prospective clinical study in the adult ED of an urban tertiary care teaching hospital. Our subjects were afebrile patients aged 18 to 65 years with localized, nondraining, purulent cutaneous abscesses requiring outpatient surgical management. Before I&D, blood for aerobic and anaerobic blood culture was drawn under sterile conditions. The wound was opened and samples for aerobic wound culture were obtained. Two and 10 minutes after I&D, blood was again drawn, from separate venipunctures. All patients were discharged home with ED follow-up scheduled 48 hours later.

RESULTS

From the 50 patients who completed the study, 150 blood samples (50 before and 100 after I&D) and 50 wound samples were obtained. No blood culture was positive, but 30 wound cultures (64%) were positive; the most commonly isolated organism was Staphylococcus aureus.

CONCLUSION

I&D of localized cutaneous abscesses in afebrile adults is unlikely to result in transient bacteremia. Larger studies are needed to determine whether routine antibiotic prophylaxis is necessary for afebrile patients undergoing I&D.

The cysteine residue responsible for the release of fibroblast growth factor-1 residues in a domain independent of the domain for phosphatidylserine binding

Fibroblast growth factor (FGF)-1 lacks a classical signal sequence to direct its secretion yet utilizes high affinity cell surface receptors to signal its heparin-dependent angiogenic and neurotrophic activities. We have previously reported that FGF-1 is released in response to temperature stress as a latent homodimer through a pathway that is potentiated by the Golgi inhibitor, brefeldin A (Jackson, A., Tarantini, F., Gamble, S., Friedman, S., and Maciag, T. (1995) J. Biol. Chem. 270, 33-36). In an attempt to further characterize this unconventional secretion mechanism, we sought to define the Cys residue(s) critical for FGF-1 dimer formation and release and to determine whether FGF-1 can associate with known phospholipid components of organelle or plasma membranes, which may be disturbed by brefeldin A. Utilizing FGF-1 Cys mutants, we were able to demonstrate that residue Cys30 is critical for FGF-1 release in response to heat shock. In addition, using solid phase phospholipid binding assays we demonstrate that FGF-1 is able to specifically associate with phosphatidylserine (PS). Heparin inhibits the association between FGF-1 and PS, and synthetic peptide competition assays suggest that the PS-binding domain of FGF-1 lies between residues 114 and 137. These observations indicate that FGF-1 may be able to associate with the PS component of organelle and/or plasma membranes and that the domains responsible for FGF-1 homodimer formation and PS binding are structurally distinct.

Identification of the domain within fibroblast growth factor-1 responsible for heparin-dependence

While the prototype members of the fibroblast growth factor (FGF) family, FGF-1 and FGF-2 are structurally related, the structural differences between these polypeptides predict that they will ultimately exhibit different biological roles. Indeed, a significant difference between these proteins is the dependence of FGF-1 on heparin for the generation of maximal mitogenic activity. In order to gain structural insight into the issue of FGF-1 heparin-dependence, a synthetic gene encoding FGF-2 was constructed with oligonucleotides in a four-cassette format similar to a synthetic gene previously constructed for FGF-1 (Forough et al. 1992, Biochem. Biophys. Acta 1090 293-298). This strategy permitted the molecular shuffling of corresponding cassette(s) between FGF-1 and FGF-2 to yield FGF-1:FGF-2 chimeras. Three amino acid changes (Lys86-->Glu, Tyr120-->His, and Thr121-->Ala) were introduced into the synthetic FGF-2 gene by the cassette format to generate convenient FGF-1 restriction sites, but these alterations did not significantly affect the mitogenic activity or the heparin-binding affinity of the recombinant FGF-2 protein when compared with native FGF-2. Among the various FGF-1:FGF-2 chimeric constructs, one designated FGF-C(1(1/2)1 1), which represents FGF-1 containing FGF-2 amino acid residues 65 to 81, displayed FGF-1-like heparin-binding affinity but it did not require the addition of exogenous heparin to manifest its mitogenic activity. These data suggest that the sequence within residues 65 and 81 from FGF-2 significantly contributes to the heparin-dependent character of FGF-1.

The Dynamic Stabilizing Innersole System (DSIS): the management of hyperpronation in children

In a study of 50 children, the Dynamic Stabilizing Innersole System (DSIS) was found to decrease the mean resting calcaneal stance position (RCSP) by an average of 6 degrees. A comparison between the neutral calcaneal stance position and the RCSP with the DSIS showed no statistically significant difference between the means for the right or left foot, indicating that the DSIS is capable of returning severe flat foot deformities to their neutral calcaneal stance position. The RCSP with and without the DSIS differed significantly, indicating that the DSIS provides a considerable and statistically significant amount of correction in the RCSP in our study population. Furthermore, the results of linear regression showed that the DSIS appears to be sensitive to the severity of the deformity, preventing overcorrection of less severe flatfoot deformities and providing a long awaited alternative to traditional pediatric corrective flatfoot devices.

The release of fibroblast growth factor-1 from NIH 3T3 cells in response to temperature involves the function of cysteine residues

Fibroblast growth factor (FGF)-1 is released from NIH 3T3 cells in response to heat shock as a biologically inactive protein that is unable to bind heparin and requires activation by (NH4)2SO4 to generate a biologically active extracellular heparin-binding growth factor (Jackson, A., Friedman, S., Zhan, X., Engleka, K. A., Forough, R., and Maciag, T. (1992) Proc. Natl. Acad. Sci. USA 89, 10691-10695). To further study the mechanism of FGF-1 release in response to heat shock (42 degrees C), we examined the kinetics of FGF-1 release from FGF-1-transfected NIH 3T3 cells and observed that the cells require at least 1 h of exposure to heat shock conditions for the release of FGF-1. Interestingly, agents that interfere with the function of the endoplasmic reticulum-Golgi apparatus, exocytosis, and the multidrug resistance pathway (brefelden A, methylamine, and verapamil, respectively) do not inhibit the release of FGF-1 in response to temperature; rather, they exaggerate the release of FGF-1. Because immunoblot analysis of FGF-1 in the conditioned medium of heat-shocked NIH 3T3 cells revealed the presence of a minor band with an apparent molecular weight of a FGF-1 homodimer and because we have previously shown that FGF-1, but not FGF-2, is able to form a homodimer in response to chemical oxidation by CuCl2 (Engleka, K. A., and Maciag, T. (1992) J. Biol. Chem. 267, 11307-11315), we examined whether reducing agents would substitute for (NH4)2SO4 and activate extracellular FGF-1. Indeed, dithiothreitol and reduced glutathione are able to individually generate a FGF-1 monomer as a heparin-binding protein from the conditioned medium of heat-shocked NIH 3T3 cell transfectants. To confirm that cysteine residues are involved in the release of FGF-1 in response to temperature, we used mutagenesis to prepare a human FGF-1 Cys-free mutant in which Cys30, Cys97, and Cys131 were converted to serine. Analysis of the release of the FGF-1 Cys-free mutant in NIH 3T3 cells transfected with the FGF-1 Cys-free mutant demonstrated that the FGF-1 Cys-free mutant is not released into the conditioned medium in response to temperature. Interestingly, exposure of the NIH 3T3 cell FGF-1 Cys-free transfectants to brefelden A followed by heat shock also demonstrated the absence of the extracellular FGF-1 Cys-free mutant.(ABSTRACT TRUNCATED AT 400 WORDS)

Peptide-priming of cytolytic T cell immunity in vivo using beta 2-microglobulin as an adjuvant

CTL recognize oligopeptides bound to MHC class I molecules. Immunization of animals with antigenic peptides has often failed to stimulate CTL responses. We confirm that immunizations with several peptides, including natural and optimally active antigenic sequences, do not prime cytotoxic immunity in mice. However, immunization with peptides together with human beta 2-microglobulin primes Ag-specific CTL. Priming is observed when animals receive injections either i.v. with ex vivo peptide/beta 2-microglobulin-pulsed cells or s.c. with an admixture of peptide and beta 2-microglobulin. beta 2-Microglobulin promotes the priming of CTL immunity if it is added with peptide, but not if it is added after cells are exposed to peptide. Synthetic peptides and mixtures of peptides from enzymatically cleaved Ag are immunogenic. When a tryptic digest of OVA or the synthetic peptide (OVA258-276) are used as immunogens, the CTL that respond recognize the endogenously processed epitope presented by an OVA-transfected target cell. The peptide + beta 2-microglobulin-primed CTL are CD4-CD8+ and are class I MHC restricted. Using the immunization protocol with beta 2-microglobulin, we have primed CTL responses with peptides from OVA, Sendai virus, and vesicular stomatitis virus. These results may explain previous failures to prime CTL with peptides in vivo and provide a novel approach for developing peptide-based vaccines for viral diseases.

Peptide-priming of cytolytic T cell immunity in vivo using beta 2-microglobulin as an adjuvant

CTL recognize oligopeptides bound to MHC class I molecules. Immunization of animals with antigenic peptides has often failed to stimulate CTL responses. We confirm that immunizations with several peptides, including natural and optimally active antigenic sequences, do not prime cytotoxic immunity in mice. However, immunization with peptides together with human beta 2-microglobulin primes Ag-specific CTL. Priming is observed when animals receive injections either i.v. with ex vivo peptide/beta 2-microglobulin-pulsed cells or s.c. with an admixture of peptide and beta 2-microglobulin. beta 2-Microglobulin promotes the priming of CTL immunity if it is added with peptide, but not if it is added after cells are exposed to peptide. Synthetic peptides and mixtures of peptides from enzymatically cleaved Ag are immunogenic. When a tryptic digest of OVA or the synthetic peptide (OVA258-276) are used as immunogens, the CTL that respond recognize the endogenously processed epitope presented by an OVA-transfected target cell. The peptide + beta 2-microglobulin-primed CTL are CD4-CD8+ and are class I MHC restricted. Using the immunization protocol with beta 2-microglobulin, we have primed CTL responses with peptides from OVA, Sendai virus, and vesicular stomatitis virus. These results may explain previous failures to prime CTL with peptides in vivo and provide a novel approach for developing peptide-based vaccines for viral diseases.

Characterization of antigen-presenting cells that present exogenous antigens in association with class I MHC molecules

Exogenous Ag in the extracellular fluids do not gain access to the class I Ag-presenting pathway in most cells. However, there is an APC resident in spleen that can process and present exogenous Ag in association with class I molecules. We characterize the phenotype of this cell. This APC is of low buoyant density, is adherent to Sepharose and glass, and expresses both class II molecules and FcR. This phenotype identifies this APC as a macrophage. Resident, peptone- and thioglycolate-induced peritoneal macrophages also display this Ag-presenting activity. Analysis with CTL clones suggest that this Ag-presenting pathway may be active in only a subset of macrophages. A similar Ag-presenting activity is also present in dendritic cell-enriched populations from spleen although we cannot rule out the possible involvement of contaminating macrophages. In contrast, B and T cells that are resident in spleen and LPS blasts are unable to present exogenous Ag in association with class I molecules. The presentation of exogenous OVA with class I molecules is not inhibited by the inhibitors of thiol proteases, leupeptin, and antipain. The presence of gelonin, a ribosomal inactivating protein, in the extracellular fluids inhibits the ability of these APC to present exogenous OVA. Under identical conditions, gelonin does not inhibit Con A-stimulated T cell proliferation, or LPS-stimulated B cell proliferation and Ag presentation. These results are discussed in relation to the potential pathways through which an Ag in the extracellular fluids is presented with MHC class I molecules.

Characterization of antigen-presenting cells that present exogenous antigens in association with class I MHC molecules

Exogenous Ag in the extracellular fluids do not gain access to the class I Ag-presenting pathway in most cells. However, there is an APC resident in spleen that can process and present exogenous Ag in association with class I molecules. We characterize the phenotype of this cell. This APC is of low buoyant density, is adherent to Sepharose and glass, and expresses both class II molecules and FcR. This phenotype identifies this APC as a macrophage. Resident, peptone- and thioglycolate-induced peritoneal macrophages also display this Ag-presenting activity. Analysis with CTL clones suggest that this Ag-presenting pathway may be active in only a subset of macrophages. A similar Ag-presenting activity is also present in dendritic cell-enriched populations from spleen although we cannot rule out the possible involvement of contaminating macrophages. In contrast, B and T cells that are resident in spleen and LPS blasts are unable to present exogenous Ag in association with class I molecules. The presentation of exogenous OVA with class I molecules is not inhibited by the inhibitors of thiol proteases, leupeptin, and antipain. The presence of gelonin, a ribosomal inactivating protein, in the extracellular fluids inhibits the ability of these APC to present exogenous OVA. Under identical conditions, gelonin does not inhibit Con A-stimulated T cell proliferation, or LPS-stimulated B cell proliferation and Ag presentation. These results are discussed in relation to the potential pathways through which an Ag in the extracellular fluids is presented with MHC class I molecules.

Inhibition of class I and class II MHC-restricted antigen presentation by cytotoxic T lymphocytes specific for an exogenous antigen

Ag in the extracellular fluids can be internalized, processed, and presented in association with class I MHC molecules on specialized APC in normal spleen. We examine the fate of these APC after they present Ag to a CTL. When splenocytes present exogenous OVA to CTL, their ability to subsequently present native Ag in association with both class I and class II molecules is inhibited. CTL do not inhibit the ability of splenocytes to present processing independent peptides with class I or class II molecules. Inhibition of Ag presentation is only observed in the presence of the specific Ag recognized by the CTL. This inhibition is MHC-restricted. In the presence of specific Ag, CTL inhibit the ability of APC to present unrelated Ag. However, bystander APC are not affected by activated CTL. Taken together these results indicate that when APC present exogenous Ag to CTL, they are inhibited or killed. The CTL that mediates this activity has a conventional CD4-CD8+ phenotype and utilizes a TCR-alpha beta. The potential significance of these findings and their possible relationship to phenomena associated with Ts cells are discussed.

Inhibition of class I and class II MHC-restricted antigen presentation by cytotoxic T lymphocytes specific for an exogenous antigen

Ag in the extracellular fluids can be internalized, processed, and presented in association with class I MHC molecules on specialized APC in normal spleen. We examine the fate of these APC after they present Ag to a CTL. When splenocytes present exogenous OVA to CTL, their ability to subsequently present native Ag in association with both class I and class II molecules is inhibited. CTL do not inhibit the ability of splenocytes to present processing independent peptides with class I or class II molecules. Inhibition of Ag presentation is only observed in the presence of the specific Ag recognized by the CTL. This inhibition is MHC-restricted. In the presence of specific Ag, CTL inhibit the ability of APC to present unrelated Ag. However, bystander APC are not affected by activated CTL. Taken together these results indicate that when APC present exogenous Ag to CTL, they are inhibited or killed. The CTL that mediates this activity has a conventional CD4-CD8+ phenotype and utilizes a TCR-alpha beta. The potential significance of these findings and their possible relationship to phenomena associated with Ts cells are discussed.

Chemical cross-linking of class I molecules on cells creates receptive peptide binding sites

Class I heterodimers on the surface of cells are generally unreceptive to binding peptides in the absence of exogenous beta 2-microglobulin. Paraformaldehyde covalently cross-links beta 2-microglobulin to class I heavy chains in situ and stabilizes empty class I heterodimers. Functionally, this cross-linking creates receptive class I peptide binding sites by acting on beta 2-microglobulin-associated molecules. The presentation of preexisting peptide-class I complexes is also enhanced. These findings support a model whereby a structural alteration, the dissociation of beta 2-microglobulin, limits the existence of receptive class I molecules on normal cells and may control the half-life of active class I molecules.

Chemical cross-linking of class I molecules on cells creates receptive peptide binding sites

Class I heterodimers on the surface of cells are generally unreceptive to binding peptides in the absence of exogenous beta 2-microglobulin. Paraformaldehyde covalently cross-links beta 2-microglobulin to class I heavy chains in situ and stabilizes empty class I heterodimers. Functionally, this cross-linking creates receptive class I peptide binding sites by acting on beta 2-microglobulin-associated molecules. The presentation of preexisting peptide-class I complexes is also enhanced. These findings support a model whereby a structural alteration, the dissociation of beta 2-microglobulin, limits the existence of receptive class I molecules on normal cells and may control the half-life of active class I molecules.

Dissociation of beta 2-microglobulin leads to the accumulation of a substantial pool of inactive class I MHC heavy chains on the cell surface

A large pool of free class I heavy chains is detected in situ on the plasma membrane of living cells. These chains are present on cells of different MHC genotypes and appear to exist under physiological conditions in vivo. These molecules arise from the dissociation of previously assembled class I heterodimers at the cell surface. The ratio of intact to dissociated heterodimers is strongly affected by the occupancy of the peptide-binding site of the class I molecule. Upon dissociation of the heterodimer, the class I molecule is functionally inactive. These findings may help to explain why class I molecules on the cell surface are unreceptive to binding peptides yet readily associate with peptides in the presence of exogenous beta 2-microglobulin. These results have implications for understanding the distinct functions of class I versus class II molecules and how the immunological identity of cells is preserved.

Presentation of exogenous antigen with class I major histocompatibility complex molecules

Soluble antigens (Ags) in the extracellular fluids are excluded from the class I major histocompatibility complex (MHC)-restricted pathway of Ag presentation in most cells. However, an exogenous Ag can be internalized, processed, and presented in association with class I MHC molecules on specialized Ag-presenting cells (APCs). These APCs express class II molecules and can simultaneously present exogenous Ags to both class I and class II MHC-restricted T cells. These APCs may be important participants in the regulation of host immune responses. This APC activity may explain several phenomena of cytotoxic T lymphocyte (CTL) priming in vivo and might be exploited for eliciting CTL responses to protein vaccines.

Generation of class I MHC-restricted T-T hybridomas

In this report we describe a system for the generation of functional, class I MHC-restricted, T-T hybridomas. The BW5147 cell line was transfected with the CD8 gene. BW5147 transfectants were obtained that stably expressed CD8 and this expression was maintained after somatic cell hybridization with activated T lymphocytes. To determine whether the stable expression of CD8 would facilitate the generation of class I MHC-specific T-T hybridomas, the transfected cells were fused with alloreactive T cells and the resultant hybrids were screened for their ability to produce lymphokines in response to antigenic stimulation. Somatic cell hybridizations with BW5147-CD8 transfectants give rise to a much higher frequency of class I MHC-specific T-T hybridomas relative to parallel fusions with BW5147. To determine whether the BW5147-CD8 transfectants would also support the generation of Ag-specific, class I MHC-restricted T-T hybridomas, they were fused with OVA-specific CTL. Several T-T hybrid clones were identified that produced lymphokines after stimulation with a transfected APC that was synthesizing OVA, or with a tryptic digest of OVA in the presence of syngeneic APC. The stimulation by Ag was MHC-restricted and mapped to the Kb molecule. An anti-CD8 mAb inhibited the stimulation of these hybridomas by Ag plus APC, whereas their stimulation by mitogen was unaffected. Cytolytic activity was not detected when several of the OVA-specific or alloreactive hybridomas were tested for their ability to kill target cells bearing the appropriate Ag. These results demonstrate that the BW5147-CD8 transfectants allow the generation of class I MHC-restricted T-T hybridomas. The potential utility of this system is discussed.

Generation of class I MHC-restricted T-T hybridomas

In this report we describe a system for the generation of functional, class I MHC-restricted, T-T hybridomas. The BW5147 cell line was transfected with the CD8 gene. BW5147 transfectants were obtained that stably expressed CD8 and this expression was maintained after somatic cell hybridization with activated T lymphocytes. To determine whether the stable expression of CD8 would facilitate the generation of class I MHC-specific T-T hybridomas, the transfected cells were fused with alloreactive T cells and the resultant hybrids were screened for their ability to produce lymphokines in response to antigenic stimulation. Somatic cell hybridizations with BW5147-CD8 transfectants give rise to a much higher frequency of class I MHC-specific T-T hybridomas relative to parallel fusions with BW5147. To determine whether the BW5147-CD8 transfectants would also support the generation of Ag-specific, class I MHC-restricted T-T hybridomas, they were fused with OVA-specific CTL. Several T-T hybrid clones were identified that produced lymphokines after stimulation with a transfected APC that was synthesizing OVA, or with a tryptic digest of OVA in the presence of syngeneic APC. The stimulation by Ag was MHC-restricted and mapped to the Kb molecule. An anti-CD8 mAb inhibited the stimulation of these hybridomas by Ag plus APC, whereas their stimulation by mitogen was unaffected. Cytolytic activity was not detected when several of the OVA-specific or alloreactive hybridomas were tested for their ability to kill target cells bearing the appropriate Ag. These results demonstrate that the BW5147-CD8 transfectants allow the generation of class I MHC-restricted T-T hybridomas. The potential utility of this system is discussed.

Comparison of a fenoterol/ipratropium combination with salbutamol from metered dose inhalers in subjects with chronic partially reversible airways obstruction

We have compared the acute bronchodilator response following salbutamol 200 micrograms and fenoterol 200 micrograms with ipratropium 80 micrograms, from metered dose inhalers in ten subjects with severe partially reversible airflow obstruction. Treatment with the combination resulted in a similar degree of bronchodilation but with a significantly longer duration of action.

Single dose comparison of salbutamol and a fenoterol/ipratropium combination from metered aerosols in patients with asthma

The single dose spirometric response to a combination metered aerosol product, fenoterol/ipratropium was compared with salbutamol from a metered aerosol in ten stable asthmatics. Two puffs from the combination aerosol (fenoterol 100 micrograms and ipratropium bromide 40 micrograms/puff) were compared with two puffs of salbutamol (100 micrograms/puff). The study was a cross-over design, using a double dummy technique and was placebo controlled. All subjects had demonstrated prior reversibility and baseline FEV1, values were within 15% on each study day.

The relationships between clinical response, psychophysiological variables and plasma levels of amitriptyline and diazepam in neurotic outpatients

In a 4 week study of the response of neurotic outpatients to treatment with amitriptyline, diazepam, amitriptyline and diazepam, or placebo clinical and psychophysiological variables and plasma levels of the drug were assessed. Clinical improvements were substantial in all treatment groups but clear relationships between clinical change, psychophysiological change and plasma levels of the drugs were not established. There was no relationship between plasma levels of the drugs and cigarette smoking. It is concluded that neither plasma levels of amitriptyline and diazepam nor change in skin conductance responsivity offer a useful guide to clinical response to drug treatment.