Evaluation of emissions and exposures at workplaces using desktop 3-dimensional printer.

There is a paucity of data on additive manufacturing process emissions and personal exposures in real-world workplaces. Hence, we evaluated atmospheres in four workplaces utilizing desktop "3-dimensional" (3-d) printers [fused filament fabrication (FFF) and sheer] for production, prototyping, or research. Airborne particle diameter and number concentration and total volatile organic compound concentrations were measured using real-time instruments. Airborne particles and volatile organic compounds were collected using time-integrated sampling techniques for off-line analysis. Personal exposures for metals and volatile organic compounds were measured in the breathing zone of operators. All 3-d printers that were monitored released ultrafine and fine particles and organic vapors into workplace air. Particle number-based emission rates (#/min) ranged from 9.4 × 109 to 4.4 × 1011 (n = 9samples) for FFF3-d printers and from 1.9 to 3.8 × 109 (n = 2 samples) for a sheer 3-d printer. The large variability in emission rate values reflected variability from the printers as well as differences in printer design, operating conditions, and feedstock materials among printers. A custom-built ventilated enclosure evaluated at one facility was capable of reducing particle number and total organic chemical concentrations by 99.7% and 53.2%, respectively. Carbonyl compounds were detected in room air; however, none were specifically attributed to the 3-d printing process. Personal exposure to metals (aluminum, iron) and 12 different organic chemicals were all below applicable NIOSH Recommended Exposure Limit values, but results are not reflective of all possible exposure scenarios. More research is needed to understand 3-d printer emissions, exposures, and efficacy of engineering controls in occupational settings.

Insights Into Emissions and Exposures From Use of Industrial-Scale Additive Manufacturing Machines.

BACKGROUND: Emerging reports suggest the potential for adverse health effects from exposure to emissions from some additive manufacturing (AM) processes. There is a paucity of real-world data on emissions from AM machines in industrial workplaces and personal exposures among AM operators. METHODS: Airborne particle and organic chemical emissions and personal exposures were characterized using real-time and time-integrated sampling techniques in four manufacturing facilities using industrial-scale material extrusion and material jetting AM processes. RESULTS: Using a condensation nuclei counter, number-based particle emission rates (ERs) (number/min) from material extrusion AM machines ranged from 4.1 × 1010 (Ultem filament) to 2.2 × 1011 [acrylonitrile butadiene styrene and polycarbonate filaments). For these same machines, total volatile organic compound ERs (µg/min) ranged from 1.9 × 104 (acrylonitrile butadiene styrene and polycarbonate) to 9.4 × 104 (Ultem). For the material jetting machines, the number-based particle ER was higher when the lid was open (2.3 × 1010 number/min) than when the lid was closed (1.5-5.5 × 109 number/min); total volatile organic compound ERs were similar regardless of the lid position. Low levels of acetone, benzene, toluene, and m,p-xylene were common to both AM processes. Carbonyl compounds were detected; however, none were specifically attributed to the AM processes. Personal exposures to metals (aluminum and iron) and eight volatile organic compounds were all below National Institute for Occupational Safety and Health (NIOSH)-recommended exposure levels. CONCLUSION: Industrial-scale AM machines using thermoplastics and resins released particles and organic vapors into workplace air. More research is needed to understand factors influencing real-world industrial-scale AM process emissions and exposures.

Recent Dieulafoy's lesion bleeding and massive pulmonary emboli. Successful use of thrombolytic therapy.

A massive GI bleed secondary to a Dieulafoy's lesion developed in a 77-year-old woman. Fifteen days later, massive pulmonary emboli developed. We describe successful thrombolytic treatment of her pulmonary emboli without complicating GI hemorrhage.

Secretion of IL-16 (lymphocyte chemoattractant factor) from serotonin-stimulated CD8+ T cells in vitro.

At sites of inflammation, mononuclear cells are in close contact with aggregated platelets. Although the physiologic role of this association is not clear, this proximity suggests that platelet-derived mediators may play a role in chemoattraction of T lymphocytes. In the current study we investigated serotonin receptor-bearing lymphocyte modulation of T cell migration. Serotonin-stimulated human blood mononuclear cells secrete lymphocyte chemoattractant activity with selective activity for CD4+ T cells. This chemoattractant activity was observed within 2 h of exposure to serotonin and was blocked by serotonin type 2 receptor antagonists. Molecular sieve chromatography of supernatant from serotonin-stimulated PBMCs revealed a single peak of T cell chemoattractant activity with an apparent molecular mass of 56 kDa and a pl of 9.1. Neutralizing experiments with specific mAbs indicated that the serotonin-induced chemotactic factor was the previously characterized lymphocyte chemoattractant factor (LCF), recently designated IL-16. Serotonin induced secretion of IL-16 from CD8+, not CD4+, T cells which did not require the de novo protein synthesis. These studies suggest that serotonin, via serotonin type 2 receptors, may promote the recruitment of CD4+ T lymphocytes into an inflammatory focus.

A comparison of the leakage of a monoclonal antibody from various immunoaffinity chromatography matrices.

Antibody leakage from immunoaffinity chromatography (IAC) matrices could reduce the working life of the IAC matrix and/or contaminate parenteral products, purified by IAC. There is therefore a need to measure the leakage of antibody from IAC matrices and to reduce such leakage. Using sensitive ELISAs it was found that the type of activated matrix, the buffer, the presence of proteases in the feedstock and the storage of IAC matrices between runs could all effect antibody leakage.

Development of enzyme-linked immunosorbent assays (ELISAs) for the detection of monoclonal antibody leakage from immunoaffinity chromatography matrices.

Antibodies can leak from immunoaffinity chromatography (IAC) matrices, reducing the working life of the IAC matrix and/or compromising the purity of the product, purified by IAC, for therapeutic use. There is therefore a need to monitor the leakage of antibody from IAC matrices. Antibody leakage from a model IAC system was measured using two-site 'non-competitive' ELISAs. Two assays were developed to measure the leakage of intact and fragmented antibody from the IAC matrix. By measuring the leakage of intact and fragmented antibody the mechanisms underlying antibody leakage from solid-supports could be elucidated.

Serotonin-stimulated aortic endothelial cells secrete a novel T lymphocyte chemotactic and growth factor.

Atherosclerotic lesions contain multiple cell types including smooth muscle cells, macrophages, and T lymphocytes. The development of an extralymphatic T lymphocyte focus of inflammation in this condition requires chemoattractant-induced cell migration and growth factor-induced cell activation. In a previous study, we described a novel 13-15-kDa T lymphocyte-specific chemotactic cytokine, endothelial cell-derived lymphocyte chemoattractant activity (ED-LCA), secreted by serotonin-stimulated bovine aortic endothelial cells that is distinct from previously identified endothelial cell-derived interleukins (IL) 1, 6, and 8. Because of the association between T lymphocyte chemotactic and growth factor activity, in the current study we investigated the effect of ED-LCA on T cell growth. We assessed its capacity to induce markers of the passage of T cells from the resting (G0) state into the G1 phase of the cell cycle, such as receptors for IL-2 (IL-2R) and transferrin (TFR) and class II major histocompatibility complex antigens (HLA-DR). Incubation of G0 freshly isolated human T lymphocytes for 48 h with chromatographically resolved, partially purified ED-LCA resulted in a threefold increase in expression of the p55 subunit of IL-2R, a threefold increase in TFR, and a twofold increase in HLA-DR. Passage into the G1 phase of the cell cycle was confirmed by cell cycle analysis employing acridine orange. Evaluation of CD4+ and CD8+ T cell subsets by double-antibody labeling demonstrated that the p55 subunit of IL-2R was induced in both T cell subsets. Although incubation of human T cells with ED-LCA alone did not induce proliferation, addition of exogenous IL-2 to T cells pulsed with ED-LCA for 24 h caused a proliferative response with a stimulation index of 3. By up-regulating functional cell surface receptors for IL-2, ED-LCA is a competence growth factor for T lymphocytes and primes them to respond to IL-2. By virtue of its effect on T cells, as a chemotactic and competence factor, this endothelial cell-derived mitoattractant could participate with other T cell growth factors like IL-2 in the recruitment and amplification of the extralymphatic T cell component of atherosclerosis.

Secretion of a novel T-lymphocyte cytokine possessing both chemotactic and growth factor activity by serotonin-stimulated human aortic endothelial cells.

The development of an extralymphatic T-lymphocyte focus of inflammation requires chemoattractant-induced cell migration and growth factor-induced cell proliferation. In a previous study, we identified a novel 13- to 15-kDa T-lymphocyte-specific chemotactic cytokine, endothelial cell-derived lymphocyte chemoattractant activity (ED-LCA), secreted by serotonin-stimulated human aortic endothelial cells. Based on its physicochemical and functional characteristics and antibody inhibition studies, ED-LCA is distinct from previously identified endothelial cell-derived IL-1, IL-6, and IL-8. Because of the association between T-lymphocyte chemotactic and growth factor activity, in the current study, we investigated the effect of ED-LCA on T cell growth by assessing its capacity to induce markers of the passage of T cells from the resting (G0) state into the G1 phase of the cell cycle, such as receptors for IL-2 (IL-2R) and transferrin (TFR), and class II major histocompatibility complex antigens (HLA-DR). Incubation of G0 freshly isolated human T lymphocytes for 48 h with chromatographically resolved, partially purified ED-LCA resulted in a threefold increase in expression of IL-2R, a threefold increase in TFR, and a twofold increase in HLA-DR. Double antibody labeling demonstrated that IL-2R was induced in both CD4+ and CD8+ T cell subsets. Although incubation of human T cells with ED-LCA alone did not induce DNA synthesis, addition of exogenous IL-2 to T cells pulsed with ED-LCA for 24 h caused an increase in DNA synthesis with a stimulation index of 3.5. By up-regulating functional cell surface receptors for IL-2 on T lymphocytes and priming them to respond to exogenous IL-2, ED-LCA is a competence growth factor. By virtue of its effect on T cells, as a chemotactic and competence factor, this endothelial cell-derived mitoattractant could participate with other T-cell growth factors like IL-2 in the generation of an extralymphatic T-lymphocyte inflammatory response.

Cytokine secretion by human aortic endothelial cells is related to degree of atherosclerosis.

We have previously described a 13- to 15-kDa T-lymphocyte-specific chemotactic protein (endothelial cell-derived lymphocyte chemoattractant activity, ED-LCA) secreted by serotonin-stimulated bovine aortic endothelial cells. In the current study, we have identified a similar serotonin-induced chemotaxin secreted by human aortic endothelial cells (HAEC). Like the bovine ED-LCA, secretion of this human T-cell chemotaxin peaked at 10(-5) M serotonin, was blocked by 5-HT2-receptor antagonists, and was not induced by other vasoactive amines, such as histamine or angiotensin II. In addition, human ED-LCA had no effect on neutrophil or monocyte migration. Using HAEC and human pulmonary arterial endothelial cells (HPAEC) from the same individual, we found that serotonin-stimulated HAEC, but not HPAEC, secreted ED-LCA. Because human vascular endothelium affected by atherosclerosis is morphologically, ultrastructurally, and phenotypically distinct from unaffected areas, we evaluated the secretion of this cytokine from cultured HAEC derived from areas of aorta differentially affected by atherosclerosis. We found that the degree of atherosclerotic involvement of an individual vessel was associated with a decrease in the uptake of serotonin and a reduction in serotonin-induced ED-LCA secretion. In response to serotonin, HAEC derived from atherosclerotic plaques did not secrete ED-LCA, whereas HAEC derived from fatty streaks secreted lesser amounts of ED-LCA than HAEC derived from normal areas. These studies demonstrate that in vivo morphological heterogeneity of HAEC is maintained in vitro and is associated with alterations in function, as measured by cytokine secretion.

Restricted secretion of a T-lymphocyte chemotactic cytokine by serotonin-stimulated cultured aortic endothelial cells.

The diversity of biologically active molecules produced by vascular endothelium suggests that the endothelial cell is an active participant in numerous physiological responses, including those of the immune system. In fact, the accumulation of T lymphocytes at extralymphatic inflammatory foci represents a series of interactions between lymphocytes and vascular endothelial cells. These interactions, however, may be modulated by other factors, such as vasoactive amines. In the current study, we report that serotonin-stimulated cultured bovine aortic endothelial cells (BAECs) secrete a T-lymphocyte chemotactic cytokine (endothelial cell-derived lymphocyte chemotactic activity [ED-LCA]). Supernatants from BAECs incubated with 10(-7)-10(-4) M serotonin (5-hydroxytryptamine [5-HT]) enhanced T-cell migration, which peaked at 10(-5) M 5-HT (235 +/- 18% control migration). ED-LCA was not stored in an active form in BAECs; its secretion occurred within 60 minutes of exposure to 5-HT and was blocked by two different 5-HT2 receptor antagonists. ED-LCA was not secreted after exposure of BAECs to histamine or angiotensin II, nor was it secreted by either 5-HT-stimulated bovine pulmonary arterial or human umbilical vein endothelial cells. Physicochemical characterization of ED-LCA demonstrated that it was a trypsin-sensitive protein with an apparent molecular mass of 13-15 kDa. Preparative isoelectric focusing demonstrated pIs of 6.0 and 7.5. When applied to a molecular sieve column, the chemotactic activity corresponding to these pIs eluted in the region of 13-15 kDa. Further investigation demonstrated that partially purified ED-LCA was specific for CD4+ and CD8+ T-lymphocyte subsets and did not enhance the migration of neutrophils or monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphocyte recruitment to the lung.

Lymphocyte recruitment in lymphoid tissues and inflammatory sites occurs in response to two events. The first is adherence of lymphocytes to specialized molecules expressed on the surface of appropriately stimulated vascular endothelial cells known as vascular addressins. The interaction occurs via specialized lymphocyte surface molecules known as homing receptors. There is considerable diversity among these molecules. At least three, and possibly four, different addressin-homing receptor pairs exist, regulating entry into peripheral lymph nodes, gut lymphoid tissue, BALT and intrathoracic lymphoid tissue, and inflamed synovium. Vascular addressins are expressed by specialized endothelial cells known as HEV. HEV are not found in normal lung parenchyma but may be induced to appear during an immune response. The mechanism for induction of HEV is unknown, although it may involve the action of inflammatory cytokines. It is not known whether separate endothelial cells exist with a propensity to develop into HEV or if any endothelial cells will develop into HEV if stimulated in the proper manner. Other accessory, lymphocyte-endothelium adhesion molecule pairs have been described, including LFA-1-ICAM-1 and CD4-HLA-DR. These molecules are induced by exposure of the endothelium to inflammatory cytokines, chiefly IFN-gamma. Thus, local humoral influences present during inflammation can alter the possibility of lymphocyte traffic through the endothelium by regulating the presence of lymphocyte adherence molecules. These processes have been documented to occur in the lung in normal homeostasis (e.g., BALT) and in disease (e.g., immunization with SRBC). After adherence, lymphocytes exit the circulation via amoeboid motility. This motility can be altered and enhanced through chemoattractant substances that act via surface receptors. The biochemical basis of cell motility is not entirely clear but appears to involve a link between the second messengers of receptor signaling and changes in the cytoskeleton, particularly actin filaments and microtubules. Like fibroblasts and smooth muscle cells, lymphocytes appear to respond to a number of "mitoattractants," substances that cause cell cycle entry and/or progression as well as enhanced motility. This relationship illustrates the integral relationship between cell motility and proliferation and suggests that the process of cell recruitment might also prime the recruitment cells to become activated to proliferate and perform effector function. Studies of lymphocyte-mediated lung disease confirm that antigen-specific as well as antigen-nonspecific lymphocytes are selectively recruited to the lung from the circulation during an inflammatory reaction in the lung.(ABSTRACT TRUNCATED AT 400 WORDS)

Histamine modulation of lymphocyte biology: membrane receptors, signal transduction, and functions.

Until recently, histamine has been considered only in the context of its being the major mediator of immediate-type hypersensitivity responses. However, subsequent investigations have demonstrated an additional role for histamine as a regulator of both cellular and humoral immune responses. In this review, we will analyze critically histamine modulation of lymphocyte biology by examining the methods employed to identify cell membrane histamine receptors, the mechanisms of signal transduction following histamine-receptor interaction, and the effects of histamine on lymphocyte function.

Pharmacotherapy of chronic obstructive pulmonary disease.

The pharmacologic treatment of the reversible elements of chronic obstructive pulmonary disease is discussed in this article. Discussion focuses on three classes of bronchodilator drugs--the sympathomimetic agents, the methylxanthines, and the anticholinergic agents. A section on corticosteroid use in patients with chronic airflow limitation is included. An integrated approach to pharmacotherapy is suggested that allows a treatment program to be designed to meet the needs of the individual patient.

Generation of, lipid neutrophil chemoattractant activity by histamine-stimulated cultured endothelial cells.

Endothelial cell-neutrophil interactions are an important aspect of inflammatory responses. Because vascular endothelial cells respond to the inflammatory mediator histamine, these studies determined whether histamine could induce endothelial cells to release substances that affect human neutrophil migration. Cultured bovine and human endothelial cells incubated with histamine released neutrophil chemoattractant activity within 1 min; peak levels were noted in 45 min. Cimetidine, an H2 receptor antagonist, blocked chemoattractant production, whereas diphenhydramine, an H1 receptor antagonist, did not. Cycloheximide did not inhibit release of chemoattractant activity, suggesting de novo protein synthesis was not necessary for its appearance. Extraction with acidified diethyl ether partitioned all neutrophil chemoattractant activity into the organic phase. The lipoxygenase pathway inhibitors, diethylcarbamazine and 5,8,11,14 eicosatetraynoic acid, inhibited generation of this lipophilic chemoattractant activity, whereas indomethacin, a cyclo-oxygenase inhibitor, did not. Resolution of the histamine-induced endothelial cell-derived chemoattractant activity by reverse-phase high pressure liquid chromatography yielded several peaks of chemoattractant activity, none of which co-eluted with leukotriene B4, platelet-activating factor, or two mono-hydroxyeicostetraenoic acids. These findings suggest that endothelial cells release lipid neutrophil chemoattractant activity that may play a role in inflammatory responses associated with histamine.