Evaluation of Immunocompetence and Biomarkers of Tolerance in Chimeric and Immunosuppression-free Kidney Allograft Recipients

BACKGROUND

Thirty-seven patients have received a living-donor kidney transplant in a phase 2 study designed to induce tolerance with facilitated allogeneic hematopoietic stem cell transplant. The study protocol is based on tolerogenic CD8 + /T-cell receptor - facilitating cells (FCR001; also including hematopoietic stem cells and αβ-T-cell receptor + T cells) and low-dose, nonmyeloablative conditioning. Persistent chimerism allowing full immunosuppression (IS) withdrawal was achieved in 26 patients (time off IS 36-123 mo).

METHODS

We evaluated biomarkers of tolerance through urinary cell mRNA profiling and immunocompetence to respond to vaccination in these patients. We also assessed kidney function and metabolic parameters compared with standard-of-care patients on IS.

RESULTS

Persistently chimeric patients retained chimerism after removal of IS and remained rejection free without donor HLA-specific antibody development. The presence of donor chimerism at >50% correlated with a signature of tolerance in urinary cell mRNA profiles, with a uniquely elevated increase in the ratio of cytotoxic T lymphocyte-associated protein 4 to granzyme B mRNA. Tolerance was associated with protection from recurrence of immune-mediated causes of kidney disease. Tolerant participants were safely vaccinated, developed protective immune responses, and did not lose chimerism after vaccination. When compared with kidney transplant recipients treated with standard IS, tolerant participants showed stable kidney function and reduced medication use for hypertension and hyperlipidemia.

CONCLUSIONS

These results suggest that elimination of IS has distinct advantages in living-donor kidney allograft recipients.

Association Between Residential Greenness and Cardiovascular Disease Risk

Background Exposure to green vegetation has been linked to positive health, but the pathophysiological processes affected by exposure to vegetation remain unclear. To study the relationship between greenness and cardiovascular disease, we examined the association between residential greenness and biomarkers of cardiovascular injury and disease risk in susceptible individuals. Methods and Results In this cross-sectional study of 408 individuals recruited from a preventive cardiology clinic, we measured biomarkers of cardiovascular injury and risk in participant blood and urine. We estimated greenness from satellite-derived normalized difference vegetation index ( NDVI ) in zones with radii of 250 m and 1 km surrounding the participants' residences. We used generalized estimating equations to examine associations between greenness and cardiovascular disease biomarkers. We adjusted for residential clustering, demographic, clinical, and environmental variables. In fully adjusted models, contemporaneous NDVI within 250 m of participant residence was inversely associated with urinary levels of epinephrine (-6.9%; 95% confidence interval, -11.5, -2.0/0.1 NDVI ) and F2-isoprostane (-9.0%; 95% confidence interval, -15.1, -2.5/0.1 NDVI ). We found stronger associations between NDVI and urinary epinephrine in women, those not on β-blockers, and those who had not previously experienced a myocardial infarction. Of the 15 subtypes of circulating angiogenic cells examined, 11 were inversely associated (8.0-15.6% decrease/0.1 NDVI ), whereas 2 were positively associated (37.6-45.8% increase/0.1 NDVI ) with contemporaneous NDVI . Conclusions Independent of age, sex, race, smoking status, neighborhood deprivation, statin use, and roadway exposure, residential greenness is associated with lower levels of sympathetic activation, reduced oxidative stress, and higher angiogenic capacity.

Dose-response relationships between internally-deposited uranium and select health outcomes in gaseous diffusion plant workers, 1948-2011

OBJECTIVE

To examine dose-response relationships between internal uranium exposures and select outcomes among a cohort of uranium enrichment workers.

METHODS

Cox regression was conducted to examine associations between selected health outcomes and cumulative internal uranium with consideration for external ionizing radiation, work-related medical X-rays and contaminant radionuclides technetium (⁹⁹ Tc) and plutonium (²³⁹ Pu) as potential confounders.

RESULTS

Elevated and monotonically increasing mortality risks were observed for kidney cancer, chronic renal diseases, and multiple myeloma, and the association with internal uranium absorbed organ dose was statistically significant for multiple myeloma. Adjustment for potential confounders had minimal impact on the risk estimates.

CONCLUSION

Kidney cancer, chronic renal disease, and multiple myeloma mortality risks were elevated with increasing internal uranium absorbed organ dose. The findings add to evidence of an association between internal exposure to uranium and cancer. Future investigation includes a study of cancer incidence in this cohort.

Mortality in a combined cohort of uranium enrichment workers

OBJECTIVE

To examine the patterns of cause-specific mortality and relationship between internal exposure to uranium and specific causes in a pooled cohort of 29,303 workers employed at three former uranium enrichment facilities in the United States with follow-up through 2011.

METHODS

Cause-specific standardized mortality ratios (SMRs) for the full cohort were calculated with the U.S. population as referent. Internal comparison of the dose-response relation between selected outcomes and estimated organ doses was evaluated using regression models.

RESULTS

External comparison with the U.S. population showed significantly lower SMRs in most diseases in the pooled cohort. Internal comparison showed positive associations of absorbed organ doses with multiple myeloma, and to a lesser degree with kidney cancer.

CONCLUSION

In general, these gaseous diffusion plant workers had significantly lower SMRs than the U.S.

POPULATION

The internal comparison however, showed associations between internal organ doses and diseases associated with uranium exposure in previous studies. Am. J. Ind. Med. 60:96-108, 2017. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Residential Proximity to Major Roadways Is Associated With Increased Levels of AC133+ Circulating Angiogenic Cells

OBJECTIVES

Previous studies have shown that residential proximity to a roadway is associated with increased cardiovascular disease risk. Yet, the nature of this association remains unclear, and its effect on individual cardiovascular disease risk factors has not been assessed. The objective of this study was to determine whether residential proximity to roadways influences systemic inflammation and the levels of circulating angiogenic cells.

APPROACH AND RESULTS

In a cross-sectional study, cardiovascular disease risk factors, blood levels of C-reactive protein, and 15 antigenically defined circulating angiogenic cell populations were measured in participants (n=316) with moderate-to-high cardiovascular disease risk. Attributes of roadways surrounding residential locations were assessed using geographic information systems. Associations between road proximity and cardiovascular indices were analyzed using generalized linear models. Close proximity (<50 m) to a major roadway was associated with lower income and higher rates of smoking but not C-reactive protein levels. After adjustment for potential confounders, the levels of circulating angiogenic cells in peripheral blood were significantly elevated in people living in close proximity to a major roadway (CD31(+)/AC133(+), AC133(+), CD34(+)/AC133(+), and CD34(+)/45(dim)/AC133(+) cells) and positively associated with road segment distance (CD31(+)/AC133(+), AC133(+), and CD34(+)/AC133(+) cells), traffic intensity (CD31(+)/AC133(+) and AC133(+) cells), and distance-weighted traffic intensity (CD31(+)/34(+)/45(+)/AC133(+) cells).

CONCLUSIONS

Living close to a major roadway is associated with elevated levels of circulating cells positive for the early stem marker AC133(+). This may reflect an increased need for vascular repair. Levels of these cells in peripheral blood may be a sensitive index of cardiovascular injury because of residential proximity to roadways.

Relationships between number, surface area, and mass concentrations of different nanoparticles in workplaces

No consistent metric for measuring exposure to nanoparticles has yet been agreed upon internationally. This study seeks to examine the relationship between the number concentration (NC), surface area concentration (SAC), and mass concentration (MC) of nanoparticles in workplaces. Real-time NC20-1000 nm, SAC10-1000 nm, and respirable MC100-1000 nm were determined for different nanoparticles. Concentration ratio (CR, activity: background), exposure ranking (ER), and between-metric correlation coefficients (R) were used to analyze the relationships between the three metrics. The ratio of cumulative percentage by number (APN) and cumulative percentage by mass (APM) was used to analyze whether the nanoparticle number is predominant, as compared with the nanoparticle mass. The CRs of NC20-1000 nm and SAC10-1000 nm for different nanoparticles at the corresponding work sites were higher than those of respirable MC100-1000 nm. The ERs of NC20-1000 nm for nano-Fe2O3 and nano-Al2O3 were the same as those of SAC10-1000 nm, but were inconsistent with those of respirable MC100-1000 nm. The order of correlation coefficients between NC20-1000 nm, SAC10-1000 nm, and respirable MC100-1000 nm was: RSAC and NC > RSAC and MC > RNC and MC. The ratios of APN and APM for nano-Al2O3 and grinding-wheel particles (less than 100 nm) at the same work site were 2.03 and 1.65, respectively. NC and SAC metrics are significantly distinct from the MC in characterizing exposure to airborne nanoparticles. Simultaneous measurements of the NC, SAC, and MC should be conducted as part of nanoparticle exposure assessment strategies and epidemiological studies.

Up-regulation of Gadd45α after exposure to metal nanoparticles: the role of hypoxia inducible factor 1α

The increased development and use of nanoparticles in various fields may lead to increased exposure, directly affecting human health. Our current knowledge of the health effects of metal nanoparticles such as cobalt and titanium dioxide (Nano-Co and Nano-TiO2 ) is limited but suggests that some metal nanoparticles may cause genotoxic effects including cell cycle arrest, DNA damage, and apoptosis. The growth arrest and DNA damage-inducible 45α protein (Gadd45α) has been characterized as one of the key players in the cellular responses to a variety of DNA damaging agents. The aim of this study was to investigate the alteration of Gadd45α expression in mouse embryo fibroblasts (PW) exposed to metal nanoparticles and the possible mechanisms. Non-toxic doses of Nano-Co and Nano-TiO2 were selected to treat cells. Our results showed that Nano-Co caused a dose- and time-dependent increase in Gadd45α expression, but Nano-TiO2 did not. To investigate the potential pathways involved in Nano-Co-induced Gadd45α up-regulation, we measured the expression of hypoxia inducible factor 1α (HIF-1α) in PW cells exposed to Nano-Co and Nano-TiO2 . Our results showed that exposure to Nano-Co caused HIF-1α accumulation in the nucleus. In addition, hypoxia inducible factor 1α knock-out cells [HIF-1α (-/-)] and its wild-type cells [HIF-1α (+/+)] were used. Our results demonstrated that Nano-Co caused a dose- and time-dependent increase in Gadd45α expression in wild-type HIF-1α (+/+) cells, but only a slight increase in HIF-1α (-/-) cells. Pre-treatment of PW cells with heat shock protein 90 inhibitor, 17-(Allylamino)-17-demethoxygeldanamycin (17-AAG), prior to exposure to Nano-Co significantly abolished Nano-Co-induced Gadd45α expression. These results suggest that HIF-1α accumulation may be partially involved in the increased Gadd45α expression in cells exposed to Nano-Co. These findings may have important implications for understanding the potential health effects of metal nanoparticle exposure.

Acrolein exposure is associated with increased cardiovascular disease risk

Background

Acrolein is a reactive aldehyde present in high amounts in coal, wood, paper, and tobacco smoke. It is also generated endogenously by lipid peroxidation and the oxidation of amino acids by myeloperoxidase. In animals, acrolein exposure is associated with the suppression of circulating progenitor cells and increases in thrombosis and atherogenesis. The purpose of this study was to determine whether acrolein exposure in humans is also associated with increased cardiovascular disease (CVD) risk.

Methods and Results

Acrolein exposure was assessed in 211 participants of the Louisville Healthy Heart Study with moderate to high (CVD) risk by measuring the urinary levels of the major acrolein metabolite—3‐hydroxypropylmercapturic acid (3‐HPMA). Generalized linear models were used to assess the association between acrolein exposure and parameters of CVD risk, and adjusted for potential demographic confounders. Urinary 3‐HPMA levels were higher in smokers than nonsmokers and were positively correlated with urinary cotinine levels. Urinary 3‐HPMA levels were inversely related to levels of both early (AC133⁺) and late (AC133⁻) circulating angiogenic cells. In smokers as well as nonsmokers, 3‐HPMA levels were positively associated with both increased levels of platelet–leukocyte aggregates and the Framingham Risk Score. No association was observed between 3‐HPMA and plasma fibrinogen. Levels of C‐reactive protein were associated with 3‐HPMA levels in nonsmokers only.

Conclusions

Regardless of its source, acrolein exposure is associated with platelet activation and suppression of circulating angiogenic cell levels, as well as increased CVD risk.

Evolving approaches of hematopoietic stem cell-based therapies to induce tolerance to organ transplants: the long road to tolerance

The immunoregulatory properties of hematopoietic stem cells (HSCs) have been recognized for more than 60 years, beginning in 1945, when Owen reported that genetically disparate freemartin cattle sharing a common placenta were red blood cell chimeras. In 1953, Billingham, Brent, and Medawar demonstrated that murine neonatal chimeras prepared by infusion of donor-derived hematopoietic cells exhibited donor-specific tolerance to skin allografts. Various approaches using HSCs in organ transplantation have gradually brought closer to reality the dream of inducing donor-specific tolerance in organ transplant recipients. Several hurdles needed to be overcome, especially the risk of graft-versus-host disease (GVHD), the toxicity of ablative conditioning, and the need for close donor-recipient matching. For wide acceptance, HSC therapy must be safe and reproducible in mismatched donor-recipient combinations. Discoveries in other disciplines have often unexpectedly and synergistically contributed to progress in this area. This review presents a historic perspective of the quest for tolerance in organ transplantation, highlighting current clinical approaches.

DNA damage caused by metal nanoparticles: involvement of oxidative stress and activation of ATM

Nanotechnology is a fast growing emerging field, the benefits of which are widely publicized. Our current knowledge of the health effects of metal nanoparticles such as nanosized cobalt (Nano-Co) and titanium dioxide (Nano-TiO(2)) is limited but suggests that metal nanoparticles may exert more adverse pulmonary effects as compared with standard-sized particles. To investigate metal nanoparticle-induced genotoxic effects and the potential underlying mechanisms, human lung epithelial A549 cells were exposed to Nano-Co and Nano-TiO(2). Our results showed that exposure of A549 cells to Nano-Co caused reactive oxygen species (ROS) generation that was abolished by pretreatment of cells with ROS inhibitors or scavengers, such as catalase and N-acetyl-L(+)-cysteine (NAC). However, exposure of A549 cells to Nano-TiO(2) did not cause ROS generation. Nano-Co caused DNA damage in A549 cells, which was reflected by an increase in length, width, and DNA content of the comet tail by the Comet assay. Exposure of A549 cells to Nano-Co also caused a dose- and a time-response increased expression of phosphorylated histone H2AX (γ-H2AX), Rad51, and phosphorylated p53. These effects were significantly attenuated when A549 cells were pretreated with catalase or NAC. Nano-TiO(2) did not show these effects. These results suggest that oxidative stress may be involved in Nano-Co-induced DNA damage. To further investigate the pathways involved in the Nano-Co-induced DNA damage, we measured the phosphorylation of ataxia telangiectasia mutant (ATM). Our results showed that phosphorylation of ATM was increased when A549 cells were exposed to Nano-Co, and this effect was attenuated when cells were pretreated with catalase or NAC. Pretreatment of A549 cells with an ATM specific inhibitor, KU55933, significantly abolished Nano-Co-induced DNA damage. Furthermore, pretreatment of A549 cells with ROS scavengers, such as catalase and NAC, significantly abolished Nano-Co-induced increased expression of phosphorylated ATM. Taken together, oxidative stress and ATM activation are involved in Nano-Co-induced DNA damage. These findings have important implications for understanding the potential health effects of metal nanoparticle exposure.

Chimerism and tolerance without GVHD or engraftment syndrome in HLA-mismatched combined kidney and hematopoietic stem cell transplantation

The toxicity of chronic immunosuppressive agents required for organ transplant maintenance has prompted investigators to pursue approaches to induce immune tolerance. We developed an approach using a bioengineered mobilized cellular product enriched for hematopoietic stem cells (HSCs) and tolerogenic graft facilitating cells (FCs) combined with nonmyeloablative conditioning; this approach resulted in engraftment, durable chimerism, and tolerance induction in recipients with highly mismatched related and unrelated donors. Eight recipients of human leukocyte antigen (HLA)-mismatched kidney and FC/HSC transplants underwent conditioning with fludarabine, 200-centigray total body irradiation, and cyclophosphamide followed by posttransplant immunosuppression with tacrolimus and mycophenolate mofetil. Subjects ranged in age from 29 to 56 years. HLA match ranged from five of six loci with related donors to one of six loci with unrelated donors. The absolute neutrophil counts reached a nadir about 1 week after transplant, with recovery by 2 weeks. Multilineage chimerism at 1 month ranged from 6 to 100%. The conditioning was well tolerated, with outpatient management after postoperative day 2. Two subjects exhibited transient chimerism and were maintained on low-dose tacrolimus monotherapy. One subject developed viral sepsis 2 months after transplant and experienced renal artery thrombosis. Five subjects experienced durable chimerism, demonstrated immunocompetence and donor-specific tolerance by in vitro proliferative assays, and were successfully weaned off all immunosuppression 1 year after transplant. None of the recipients produced anti-donor antibody or exhibited engraftment syndrome or graft-versus-host disease. These results suggest that manipulation of a mobilized stem cell graft and nonmyeloablative conditioning represents a safe, practical, and reproducible means of inducing durable chimerism and donor-specific tolerance in solid organ transplant recipients.

Combination effects of cigarette smoke extract and ambient ultrafine particles on endothelial cells

Previous studies have shown that ambient ultrafine particles with diameters less than 100nm (UFPs) can pass from the lungs to the circulation because of their very small diameter, and induce lung oxidative stress with a resultant dysfunction of lung endothelial cells. However, no studies have addressed the potential combined effects of UFPs and cigarette smoke on vascular endothelial cells. We hypothesized that co-exposure to UFPs and cigarette smoke extract (CSE) may cause combined effects on activation of endothelial cells and dysfunction of endothelium by oxidative stress through activation of NADPH oxidase. We determined the effects of UFPs with or without CSE on mouse pulmonary microvascular endothelial cells (MPMVEC) obtained from C57BL/6J (wild-type) and gp91(phox) knock-out mice (gp91(phox) is one of the key components of NADPH oxidase, one of ROS generators). Our results showed that exposure of MPMVEC from wild-type mice to UFPs or CSE, at a non-toxic dose, induced reactive oxygen species (ROS) generation, increased phosphorylation of p38 and Erk1/2, and up-regulated early growth response -1 (Egr-1) and IL-6 genes. These effects were significantly enhanced when cells were co-exposed to both UFPs and CSE. However, exposure of MPMVEC from gp91(phox) knock-out mice did not induce the above effects. Furthermore, UFPs- and/or CSE-induced Egr-1 mRNA upregulation was attenuated significantly when cells were pre-treated with p38 specific inhibitor, SB 203580, or MEK1/2 inhibitor, PD98059, and Egr-1 siRNA treatment abolished UFPs- and/or CSE-induced overexpression of IL-6. Our results suggest that UFPs and/or CSE caused activation of NADPH oxidase, resulting in ROS generation that led to activation of MAPKs through induced phosphorylation of p38 and ERK1/2 MAPKs and upregulation of Egr-1. Those effects may further result in endothelial dysfunction through production of cytokines such as IL-6. Our results suggest that co-exposure to UFPs and CSE causes enhanced injury to endothelial cells.

The role of hypoxia inducible factor-1α in the increased MMP-2 and MMP-9 production by human monocytes exposed to nickel nanoparticles

Nickel is an important economic commodity, but it can cause skin sensitization and may cause lung diseases such as lung fibrosis, pneumonitis, bronchial asthma and lung cancer. With development of nanotechnology, nano-sized nickel (Nano-Ni) and nano-sized titanium dioxide (Nano-TiO₂) particles have been developed and produced for many years with new formulations and surface properties to meet novel demands. Our previous studies have shown that Nano-Ni instilled into rat lungs caused a greater inflammatory response as compared with standard-sized nickel (5 μm) at equivalent mass concentrations. Nano-Ni caused a persistent high level of inflammation in lungs even at low doses. Recently, several studies have shown that nanoparticles can translocate from the lungs to the circulatory system. To evaluate the potential systemic effects of metal nanoparticles, we compared the effects of Nano-Ni and Nano-TiO₂ on matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) gene expression and activity. Our results showed that exposure of human monocyte U937 to Nano-Ni caused dose- and time- dependent increase in MMP-2 and MMP-9 mRNA expression and pro-MMP-2 and pro-MMP-9 activity, but Nano-TiO₂ did not. Nano-Ni also caused dose- and time- related increase in tissue inhibitor of metalloproteinases 1 (TIMP-1), but Nano-TiO₂ did not. To determine the potential mechanisms involved, we measured the expression of hypoxia inducible factor 1α (HIF-1α) in U937 cells exposed to Nano-Ni and Nano-TiO₂. Our results showed that exposure to Nano-Ni caused HIF-1α accumulation in the nucleus. Furthermore, pre-treatment of U937 cells with heat shock protein 90 (Hsp90) inhibitor, 17-(Allylamino)-17-demethoxygeldanamycin (17-AAG), prior to exposure to Nano-Ni significantly abolished Nano-Ni-induced MMP-2 and MMP-9 mRNA upregulation and increased pro-MMP-2 and pro-MMP-9 activity. Our results suggest that HIF-1α accumulation may be involved in the increased MMP-2 and MMP-9 production in U937 cells exposed to Nano-Ni.

Occupational exposure to trichloroethylene and cancer risk for workers at the Paducah Gaseous Diffusion Plant

OBJECTIVE

The Paducah Gaseous Diffusion Plant (PGDP) became operational in 1952; it is located in the western part of Kentucky. We conducted a mortality study for adverse health effects that workers may have suffered while working at the plant, including exposures to chemicals.

MATERIALS AND METHODS

We studied a cohort of 6820 workers at the PGDP for the period 1953 to 2003; there were a total of 1672 deaths to cohort members. Trichloroethylene (TCE) is a specific concern for this workforce; exposure to TCE occurred primarily in departments that clean the process equipment. The Life Table Analysis System (LTAS) program developed by NIOSH was used to calculate the standardized mortality ratios for the worker cohort and standardized rate ratio relative to exposure to TCE (the U.S. population is the referent for ageadjustment). LTAS calculated a significantly low overall SMR for these workers of 0.76 (95% CI: 0.72-0.79). A further review of three major cancers of interest to Kentucky produced significantly low SMR for trachea, bronchus, lung cancer (0.75, 95% CI: 0.72-0.79) and high SMR for Non-Hodgkin's lymphoma (NHL) (1.49, 95% CI: 1.02-2.10).

RESULTS

No significant SMR was observed for leukemia and no significant SRRs were observed for any disease. Both the leukemia and lung cancer results were examined and determined to reflect regional mortality patterns. However, the Non-Hodgkin's Lymphoma finding suggests a curious amplification when living cases are included with the mortality experience.

CONCLUSIONS

Further examination is recommended of this recurrent finding from all three U.S. Gaseous Diffusion plants.

Mortality patterns among Paducah Gaseous Diffusion Plant workers

OBJECTIVE

To determine whether Paducah Gaseous Diffusion Plant workers had mortality patterns that differed from the general US population and to investigate whether mortality patterns were associated with job title or workplace exposures.

METHODS

A retrospective occupational cohort mortality study was conducted on 6759 workers. Standardized mortality ratio analyses compared the cohort with the referent US population. Internal comparisons producing standardized rate ratios were conducted by job title, metal exposure, and cumulative internal and external radiation exposures.

RESULTS

Overall mortality and cancer rates were lower than the referent population, reflecting a strong healthy worker effect. Individual not significant standardized mortality ratios and standardized rate ratios were noted for cancers of the lymphatic and hematopoietic tissue.

CONCLUSIONS

Although relatively low exposures to radiation and metals did not produce statistically significant health effects, no significant elevations for lymphatic and hematopoietic cancers were consistent with previous studies of nuclear workers.

Physiological and psychophysical comparison between a lifting task with identical weight but different coupling factors

The objective of the revised NIOSH (National Institute for Occupational Safety and Health) lifting equation is to prevent or reduce lifting-related injuries. The coupling component of the equation relates to quality of the grip (i.e., hand-to-object interface) and can be rated good, fair, or poor. Good coupling is theorized to reduce lifting stress, whereas poor coupling is theorized to increase lifting stress. This study compared the physiological and psychophysical stress between a lifting task with identical weight but different coupling factors. Subjects (n = 21; 26 +/- 6 years; 177.8 +/- 7.8 cm; 73.9 +/- 10.7 kg) transferred a milk crate or bag of dog food each weighing 12.5 kg back and forth from the floor to a table for 2, paced, 5-minute work bouts. Steady-state metabolic data were used to compare the lifting tasks. Results showed significantly higher oxygen consumption, caloric cost, heart rate, and rating of perceived exertion during the lifting task using the milk crate vs. the bag of dog food (p < 0.05). No difference in respiratory exchange ratio was observed (p > 0.05). In conclusion, a significantly higher metabolic cost and perceived exertion was observed when subjects performed a paced two-handed lifting task with good coupling factors than when using an object with poor coupling factors. When lifting stress is measured by metabolic cost and perceived exertion, these results are in contrast to expectations that a poor quality grip (i.e., poor coupling) would increase stress of a lifting task. Results of this study may help the work-place practitioner make decisions related to the use of the revised NIOSH lifting equation in the design and pacing of lifting-related tasks. Improved decision making may benefit productivity and enhance injury prevention in the workplace.

Diabetes is associated with increased sensitivity of alveolar macrophages to urban particulate matter exposure

Many epidemiological studies and animal experiments have shown that individuals with preexisting diseases, such as asthma, chronic obstructive pulmonary disease (COPD), and diabetes mellitus (DM) are more susceptible to particulate matter (PM)-related health problems. However, the mechanisms underlying this susceptibility are still unclear. PM has been shown to affect macrophage functions. We hypothesized that exposure to PM in the setting of DM and high glucose levels would result in enhanced macrophage activation. Rabbits were rendered diabetic with alloxan administered intravenously. Blood glucose concentration was measured daily for the first several weeks and weekly thereafter using a blood glucose meter. After 9 months of diabetes (blood glucose great than 450mg/dl), rabbits were sacrificed and bronchoalveolar lavage was performed to collect alveolar macrophages. Alveolar macrophages were exposed in vitro to urban particulate matter SRM 1648 (U-PM). Our results showed that U-PM caused dose-dependent cytotoxic effects, and these effects were significantly higher in macrophages obtained from DM rabbits than those from normal rabbits. Reactive oxygen species (ROS) generation in macrophages from DM rabbits with exposure to U-PM was also greater than in macrophages from normal rabbits. Our results also showed that exposure of macrophages to U-PM caused an increase in cytokine mRNA expression level and activity of matrix metalloproteinase 9 (MMP-9), but not MMP-2, and that these effects were greater in macrophages from DM rabbits. These results demonstrate that U-PM caused severe oxidative stress in macrophages from DM rabbits and up-regulation of cytokine expression and MMP-9 activity.

Activation of endothelial cells after exposure to ambient ultrafine particles: the role of NADPH oxidase

Several studies have shown that ultrafine particles (UFPs) may pass from the lungs to the circulation because of their very small diameter, and induce lung oxidative stress with a resultant increase in lung epithelial permeability. The direct effects of UFPs on vascular endothelium remain unknown. We hypothesized that exposure to UFPs leads to endothelial cell O(2)(-) generation via NADPH oxidase and results in activation of endothelial cells. Our results showed that UFPs, at a non-toxic dose, induced reactive oxygen species (ROS) generation in mouse pulmonary microvascular endothelial cells (MPMVEC) that was inhibited by pre-treatment with the ROS scavengers or inhibitors, but not with the mitochondrial inhibitor, rotenone. UFP-induced ROS generation in MPMVEC was abolished by p67(phox) siRNA transfection and UFPs did not cause ROS generation in MPMVEC isolated from gp91(phox) knock-out mice. UFP-induced ROS generation in endothelial cells was also determined in vivo by using a perfused lung model with imaging. Moreover, Western blot and immunofluorescence staining results showed that MPMVEC treated with UFPs resulted in the translocation of cytosolic proteins of NADPH oxidase, p47(phox), p67(phox) and rac 1, to the plasma membrane. These results demonstrate that NADPH oxidase in the pulmonary endothelium is involved in ROS generation following exposure to UFPs. To investigate the activation of endothelial cells by UFP-induced oxidative stress, we determined the activation of the mitogen-activated protein kinases (MAPKs) in MPMVEC. Our results showed that exposure of MPMVEC to UFPs caused increased phosphorylation of p38 and ERK1/2 MAPKs that was blocked by pre-treatment with DPI or p67(phox) siRNA. Exposure of MPMVEC obtained from gp91(phox) knock-out mice to UFPs did not cause increased phosphorylation of p38 and ERK1/2 MAPKs. These findings confirm that UFPs can cause endothelial cells to generate ROS directly via activation of NADPH oxidase. UFP-induced ROS lead to activation of MAPKs through induced phosphorylation of p38 and ERK1/2 MAPKs that may further result in endothelial dysfunction through production of cytokines such as IL-6. Our results suggest that endothelial oxidative stress may be an important mechanism for PM-induced cardiovascular effects.

Matrix metalloproteinase-2 and -9 are induced differently by metal nanoparticles in human monocytes: The role of oxidative stress and protein tyrosine kinase activation

Recently, many studies have shown that nanoparticles can translocate from the lungs to the circulatory system. As a particulate foreign body, nanoparticles could induce host responses such as reactive oxygen species (ROS) generation, inflammatory cytokine and matrix metalloproteinase (MMP) release which play a major role in tissue destruction and remodeling. However, the direct effects of nanoparticles on leukocytes, especially monocytes, are still unclear. The objective of the present study was to compare the ability of Nano-Co and Nano-TiO(2) to cause alteration of transcription and activity of MMPs and to explore possible mechanisms. We hypothesized that non-toxic doses of some transition metal nanoparticles stimulate an imbalance of MMP/TIMP that cause MMP production that may contribute to their health effects. To test this hypothesis, U937 cells were treated with Nano-Co and Nano-TiO(2) and cytotoxic effects and ROS generation were measured. The alteration of MMP-2 and MMP-9 expression and activity of MMP-2 and MMP-9 after exposure to these metal nanoparticles were subsequently determined. To investigate the potential signaling pathways involved in the Nano-Co-induced MMP activation, the ROS scavengers or inhibitors, AP-1 inhibitor, and protein tyrosine kinase (PTK) inhibitors were also used to pre-treat U937 cells. Our results demonstrated that exposure of U937 cells to Nano-Co, but not to Nano-TiO(2), at a dose that does not cause cytotoxicity, resulted in ROS generation and up-regulation of MMP-2 and MMP-9 mRNA expression(..) Our results also showed dose- and time-related increases in pro-MMP-2 and pro-MMP-9 gelatinolytic activities in conditioned media after exposure of U937 cells to Nano-Co, but not to Nano-TiO(2). Nano-Co-induced pro-MMP-2 and pro-MMP-9 activity increases were inhibited by pre-treatment with ROS scavengers or inhibitors. We also demonstrated dose- and time-related decreases in tissue inhibitors of metalloproteinases 2 (TIMP-2) in U937 cells after exposure to Nano-Co, but not to Nano-TiO(2). However, neither Nano-Co nor Nano-TiO(2) exposure led to any transcriptional change of TIMP-1. The decrease of TIMP-2 after exposure to Nano-Co was also inhibited by pre-treatment with ROS scavengers or inhibitors. Our results also showed that pre-treatment of U937 cells with AP-1 inhibitor, curcumin, or the PTK specific inhibitor, herbimycin A or genistein, prior to exposure to Nano-Co, significantly abolished Nano-Co-induced pro-MMP-2 and-9 activity. Our results suggest that Nano-Co causes an imbalance between the expression and activity of MMPs and their inhibitors which is mediated by the AP-1 and tyrosine kinase pathways due to oxidative stress.

Underestimation of mortality due to chronic obstructive pulmonary disease (COPD) in Kentucky

BACKGROUND

Chronic obstructive pulmonary disease (COPD) mortality may be underestimated because it is frequently listed as a contributory cause of death, rather then the underlying cause of death, on state death certificates. Contributory causes of death are not counted in mortality statistics. This may underestimate the true burden of disease.

OBJECTIVE

Determine the frequency in which COPD is listed as a contributory cause of death, rather than the underlying cause of death, per state mortality records for a one-year period, year 2000.

METHODS

15,036 mortality records from Kentucky death certificates were examined for year 2000 for all deaths due to diseases most often associated with COPD; notably, heart disease, pneumonia/influenza, and asthma.

RESULTS

Cases in which COPD was listed as a contributory cause of death for asthma, pneumonia and influenza was small (less than 1%). Cases in which COPD was listed as a contributory cause of death for heart disease was much higher at 6.8% (824 out of 12,084). Counting these cases increases the COPD age-adjusted mortality rate 39%, from 52.4 to 72.7/ 100,000 people.

CONCLUSION

This study provided evidence to generate and support the hypothesis that COPD mortality is underestimated in Kentucky when the underlying cause of death is heart disease, thus underestimating the true burden of disease. COPD is a chronic, often severe disease commonly associated with comorbid conditions such as heart disease that ultimately lead to death, but which may not be accurately reflected in mortality statistics. Accurate reporting is essential for health planning, education, research, and treatment options.

Depression and Occupational Injury: Results of a Pilot Investigation

OBJECTIVE

Even mild clinical depression can cause decreased vigilance, attention span, increased irritability, and insomnia-all well-known precursors to occupational injury. This pilot project explores the relationship between occupational injury and depression.

METHOD

One hundred twenty-one individuals with recent work-related injuries and 140 without work-related injuries completed a self-administered depression screening instrument (PHQ-9). We compared the two groups using bivariate analyses. The impact of depression on injury was examined using logistic regression analysis controlling for employment history, marital status, age, and sex.

RESULTS

Overall, injured workers in this study were not more likely to be depressed than a comparison group of uninjured workers. However, injured women had significantly higher depression scores than non-injured women (P = 0.04); no such difference was found for men.

CONCLUSIONS

These data suggest that depression may serve as a precursor to occupational injury for women.

Serum interferon-gamma is associated with longitudinal decline in lung function among asthmatic patients: the Normative Aging Study

BACKGROUND

Cytokines are important mediators of the asthmatic response. A retrospective pilot study showed that serum levels of interleukin (IL)-5 and interferon (IFN)-gamma were related to lung function decline among asthmatic patients over the preceding 3 years. To confirm these findings, we tested the hypothesis that serum cytokines are associated with longitudinal lung function decline.

METHODS

We conducted a prospective, longitudinal study of 25 asthmatic and 50 nonasthmatic men (median age, 63 years; range, 45 to 80 years) participating in the Normative Aging Study. All study subjects completed two consecutive triennial examinations, including spirometry, methacholine challenge testing, allergy skin testing, and phlebotomy. Serum levels were measured for IL-4, IL-5, IL-6, IL-8, IL-10, and IFN-gamma.

RESULTS

Among asthmatic patients, a higher initial serum level of IFN-gamma was associated with a greater rate of decline of forced expiratory volume in 1 second (FEV1; beta = -67 mL/year per log increase in serum IFN-gamma, P = 0.04) and, to a lesser extent, of FEV1/forced vital capacity ratio (beta = -0.91%/year per log increase in serum IFN-gamma, P = 0.07) after adjusting for age, smoking status, and baseline level of lung function. Serum IL-5 level was associated with a rate of decline in FEV1 of borderline significance (beta = -61 mL/year per log increase in serum IL-5, P = 0.08) among asthmatic patients. These relationshipswere not observed among nonasthmatic patients.

CONCLUSIONS

Serum levels of IFN-gamma are associated with subsequent rate of change in lung function among asthmatic patients in this cohort of middle-aged and older men, and may be useful as biologic markers of risk for accelerated lung function decline in population studies.

The relation between serum cytokine levels and common laboratory tests in healthy Japanese males

OBJECTIVES

Cytokines are critical regulatory molecules that circulate in blood at measurable levels. However, the epidemiology of serum cytokine levels in healthy populations is still limited, particularly for Japanese populations. The objective of this study was to examine the relation between serum cytokine levels and common laboratory tests in a healthy Japanese population.

METHODS

We studied serum levels of six cytokines (interleukin-4 (IL-4), IL-5, IL-6, IL-10, interferon-γ (IFN-γ), granulocyte-macrophage colony-stimulating factor (GM-CSF)) in a healthy Japanese population using a sensitive chemiluminescence ELISA (CL-ELISA). We examined the relations between serum cytokine levels and common laboratory tests using multiple regression analysis. We were particularly interested in potential relations between serum cytokine levels and C-reactive protein (CRP) in light of its relation to the risk of cardiovascular events. We also investigated the relation between cytokine levels, alcohol consumption and smoking.

RESULTS

After adjusting for the influence of other cytokines and laboratory tests, the serum level of IL-4 was associated with IL-5 and GM-CSF. In addition to IL-4, IL-5 was also associated with IL-10 and IFN-γ. IL-6 was associated with IL-10 and IFN-γ, and IL-10 and IFN-γ were associated with GM-CSF. CRP was significantly negatively associated with serum IL-4 level. IL-6 was weakly correlated with alcohol consumption level in this population. IL-5 among smokers tended to be lower than that among nonsmokers.

CONCLUSIONS

Close relations among serum cytokine levels were observed in a healthy population. It is interesting that the level of IL-4, an anti-inflammatory cytokine, was inversely related to CRP level, suggested to be a marker of inflammation.

Serum cytokine levels, cigarette smoking and airway responsiveness among pregnant women

BACKGROUND

Five to twenty percent of healthy, nonasthmatic individuals exhibit airway hyperreactivity. Because cytokines are important intermediates in airway responses, we investigated the relationship between serum cytokines and airway responsiveness in a well-characterized population of pregnant women.

METHODS

We analyzed serum levels of interleukin-4 (IL-4), IL-5, IL-6, interferon-gamma (IFN-gamma), and granulocyte-macrophage colony-stimulating factor (GM-CSF) in frozen sera from 240 pregnant nonasthmatic subjects from a previous study of airway responsiveness and preterm labor for their relationship to methacholine challenge test results.

RESULTS

Serum IFN-gamma and GM-CSF levels were significantly related to levels of methacholine airway responsiveness among nonasthmatics in this population. Nonasthmatics with PD(20) <8 micromol (the highest level of airway responsiveness) had the highest mean serum levels of IFN-gamma and GM-CSF, those with 8 <or= PD(20) <or= >50 micromol had intermediate levels, and those with PD(20) >>50 mol had the lowest levels. Both serum IFN-gamma and GM-CSF levels were also significantly related to the log dose-response slope for methacholine responsiveness. These relationships were confirmed in a multiple linear regression analysis controlling for age, ethnic background, and cigarette smoking. Current smoking was uniformly associated with decreased cytokine levels.

CONCLUSION

IFN-gamma, GM-CSF, and other cytokines may be useful serum markers in population studies of airway responsiveness.

Managed care in workers' compensation plans

Workers' compensation plans have lagged behind most public and private health care plans in the adoption of managed care techniques. This is largely attributable to the underlying differences between workers' compensation and group health plans. Managed care techniques were developed within group health plans with the objective of health at the lowest cost. In workers' compensation, managed care must address a different objective-restoring a worker to health and productivity at the lowest cost. It is this fundamental difference that makes the application of managed care techniques to workers' compensation plans contentious and at times inappropriate. Research on the impact of managed care on the health and welfare of injured workers is sparse, and important questions remain about the appropriateness of care delivered under workers' compensation managed care plans. In this paper, we discuss the application of managed care to workers' compensation, and highlight the barriers to effective implementation.

Serum neopterin, beta2-microglobulin, soluble interleukin-2 receptors, and immunoglobulin levels in healthy adolescents

Serum biomarkers, such as neopterin, beta2-microglobulin (B2M), and soluble interleukin-2 receptors (sIL-2R), are elevated in viral infections, including HIV-1 infection, and in inflammatory conditions, autoimmune disease, and malignancies. For many of these conditions, serum levels correlate with disease activity. Application of these biomarkers in adolescents is limited by a lack of information on the range and determinants of variability (age, sex, race) for serum levels of these important molecules in this age group. To address this question, we analyzed serum samples from a well-characterized heterogeneous population of 111 healthy adolescents. White children had significantly higher serum levels of sIL-2R and IgM and lower levels of IgG (P </= 0.001) than black children. Boys had higher sIL-2R and B2M levels (P < 0.005) and lower IgM levels (P < 0.05) than girls. No significant age effect on B2M or neopterin level was observed over the age range of 12-19 years included in this analysis. However, stratification by race showed that serum sIL-2R level was significantly associated with age among whites, but not among blacks. Values of these biomarkers in this population are compared with age-stratified values in the previously analyzed 20- to 69-year-old population from whose households the adolescent subjects were recruited.

Molecular markers of acute upper airway inflammation in workers exposed to fuel-oil ash

Biomarkers in nasal lavage (NL) fluid may be useful in determining the presence and severity of upper airway inflammation. We studied 18 boilermakers overhauling a large, oil-fired boiler and 11 utility workers who served as controls for 6 wk. NL was performed before (NL1), during (NL2), and after (NL3) the overhaul. We measured nasal fluid levels of interleukins 6 (IL-6) and 8 (IL-8), eosinophilic cationic protein (ECP), and myeloperoxidase (MPO) as markers of response to fuel-oil ash exposure. In boilermakers, MPO was elevated during boiler work versus preboiler work (mean = 33.8 versus 22.7 ng/ml, p < 0.05), and at the 2-wk postexposure lavage (NL3) it had declined to 24.2 ng/ml (p = 0.08). Mean IL-8 levels increased in boilermakers between NL1 and NL2 (mean = 83.8 versus 134.8 pg/ml, p < 0.05), then decreased at NL3 (mean = 134.8 versus 89.0 pg/ml, p < 0.05). Nasal fluid vanadium increased in boilermakers between NL1 and NL2 (median < 1.0 versus 4.7 ppb, respectively, p < 0.05), then decreased at NL3 (median, 4.7 versus < 1.0 ppb, respectively, p < 0. 05). Levels of IL-6 and ECP did not change significantly during the study. Utility workers showed no significant change in any marker during the study period. Particulate matter < 10 micro(m) (PM10) levels were higher for boilermakers than for utility workers before boiler work (geometric mean (GM) = 0.40 versus 0.10 mg/m3, p < 0.05). This difference was more significant during boiler work (GM = 0.47 versus 0.13 mg/m3, p < 0.001). Ozone levels were low during the study. These data suggest that exposure to fuel-oil ash results in acute upper airway inflammation, potentially mediated by increased IL-8 levels and the recruitment and activation of polymorphonuclear leukocytes. These changes were associated with significantly increased PM10 levels and concentrations of upper airway vanadium.

Elevated serum interferon-gamma in atopic asthma correlates with increased airways responsiveness and circadian peak expiratory flow variation

Interleukin (IL)-4, IL-5 and interferon (IFN)-gamma are thought to play an important role in chronic airway inflammation in asthmatic subjects. Increased airways responsiveness and nocturnal airway obstruction are important clinical manifestations of asthma. The aim of this study was to investigate whether IL-4, IL-5 and IFN-gamma values are elevated in atopic asthma and correlate with its clinical manifestations. Serum IL-4, IL-5 and IFN-gamma levels of 17 atopic asthmatics and eight nonatopic healthy subjects were determined at 16:00 and 04:00 h by a chemiluminescence enzyme-linked immunosorbent assay (ELISA) method. The clinical manifestation of asthma was determined by assessment of the degree of airway obstruction, airways responsiveness to methacholine and severity of nocturnal airway obstruction, defined as the mean circadian (16:00-04:00 h) peak expiratory flow (PEF) variation. Serum IL-4, IL-5 and IFN-gamma levels were significantly higher in asthmatic subjects as compared to healthy controls, both at 16:00 and 04:00 h. In asthmatic subjects serum IFN-gamma at both time points correlated significantly with the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (PC20,meth) (rho= - 0.55) and with the mean 16:00-04:00 h PEF variation (rho = 0.53). In contrast, no relationship was found between the levels of IL-4 and IL-5 and the parameters of clinical manifestation of asthma. The results suggest that the serum interferon-gamma level is a reflection of the severity of airway inflammation in atopic asthma. More studies are needed to detect the cellular sources and to clarify the exact roles of interferon-gamma and other pro-inflammatory cytokines in asthma.

Blood interleukin-8 production is increased in chemical workers with bronchitic symptoms

Chemical exposure may result in respiratory conditions such as chronic bronchitis, bronchial hyperresponsiveness, and chronic airway obstruction. Clinical studies have shown that during the course of disease, cytokine networks are changed. In order to study the relationship between blood cytokines and respiratory symptoms in an occupational setting, we investigated 106 chemical workers during a routine yearly medical examination in 1995. Lung function was measured with flow volume curves and impedance using the forced oscillation technique (FOT). Smoking-status and respiratory symptoms were determined by questionnaires. Cytokines were selected on biological plausibility and measured both in a whole blood assay (TNF-alpha, IL-8) and in serum (IL-4, IL-5, IL-6, IFN-gamma). The hypothesis is that blood levels of TNF-alpha and IL-8 are increased in bronchitis, while serum levels of IL4, IL-5 are increased and IFN-gamma is decreased in asthmatic workers. Spontaneous IL-8 release was significantly higher in workers with bronchitis (P < 0.05) or chronic bronchitis (P < 0.01) compared to workers without those respiratory symptoms, also after correction for age, pack-years, and blood lymphocyte numbers or compared to a matched control group. No correlation was present between specific cytokines and asthmatic symptoms. These data suggest that blood IL-8 may be considered as a useful marker for bronchitis.

Temporal variability in immunological parameters: peripheral blood mononuclear cell subsets, serum immunoglobulins, and soluble markers of immune system activation

T-cell subsets and soluble factors of immune system activation are increasingly used as biologic markers of disease and predictors of disease progression. For example, changes in CD4 cells and CD4:CD8 ratio, sIL-2R, B2M, neopterin, and IgA have been used in predicting AIDS onset and progression. We examined the temporal variability of T-cell subsets, monocytes, natural killer cells, B cells, immunoglobulins, soluble interleukin-2 receptor (sIL-2R), neopterin, and beta-2 microglobulin (B2M) among 135 adults tested at two time points approximately 3 months apart. The purpose of the study was two-fold: (1) to assess the stability of these measures at two points in time, and (2) to investigate which parameters tend to track together over time, i.e., show significant longitudinal correlation. Mean population values for these immunologic parameters remained remarkably stable over the 3-month period. However, individual subjects exhibited significant temporal variability for many parameters. Unlike observations in patients with AIDS, changes in immunoglobulins and other soluble factors were not significantly correlated with changes in cellular subsets over the same period. However, change in B2M was correlated with change in neopterin (r = .35, p < or = .0001), and change in IgA was correlated with changes in IgG and IgM (r = .44, r = .54, P < or = .001 for both). Characterizing this temporal variability in a healthy population provides important information for researchers applying these tests in clinical and epidemiological studies.

Lymphocyte function and cytokine production during incremental exercise in active and sedentary males and females

This study examined the effects of acute continuous incremental exercise on lymphocyte mitogenic function and cytokine production in physically active and sedentary males and females. Physically active (n = 32) and sedentary (N = 32) male and female subjects were randomly assigned to an exercise or control condition. Exercise involved a continuous incremental protocol consisting of cycling for 3 periods of 6 min at workrates corresponding to 55%, 70% and 85% VO2peak. Blood samples were drawn from a venous catheter at baseline, 6 min, 12 min and 18 min, and 2 h following completion of exercise. Relative to baseline and control condition the percentage of T (CD3+) and B cells (CD19+) significantly decreased, and the percentage of NK cells (CD3-CD16+CD56+) increased (p < 0.001) during each stage of the incremental exercise test. The proliferative response to ConA was suppressed, enhanced, or unchanged using 1.25 micrograms/ml, 2.5 micrograms/ml and 5.0 micrograms/ml ConA, respectively. The in-vitro production of IL-1 and IFN-gamma increased during each workload. In contrast IL-4 production did not change during exercise. The resting and exercise induced alterations in lymphocyte function and cytokine production were independent of gender and fitness level, and returned to baseline 2 h into recovery. The in-vitro production of IFN-gamma and IL-4 suggests that physical activity may alter the balance of TH1 and TH2 lymphocytes.

Endometrial Th2 cytokine expression throughout the menstrual cycle and early pregnancy

Embryonic implantation and maintenance of pregnancy is influenced by the maternal immunological response. Type 2 T-helper (Th2) cells secrete interleukins 4, 5, 6 and 10 and are associated with suppression of cell-mediated immunity. Temporal changes in the expression of these cytokines were detectable by immunohistochemistry throughout the menstrual cycle. In pregnancy, 10-fold or greater increases in interleukin 6 and 10 secretion were detectable by enzyme-linked immunoassay compared with the non-pregnant state. The pattern of expression of Th2 cytokines suggests that progesterone may influence endometrial cytokine secretion. During pregnancy, Th2 expression paralleled that of vimentin, a stromal cell marker, suggesting that these cells may be a principal source of Th2 cytokines may be a mechanism of suppressing cell-mediated immunity in the endometrium, which may in turn enhance embryonic implantation and maintenance of pregnancy.

[Chemiluminescence assays for cytokines in serum: influence of age, smoking, and race in healthy subjects]

Evidence is accumulating that cytokines are important intermediates in the pathogenesis of many diseases such as asthma and pulmonary fibrosis. However, a major limitation to clinical studies of cytokines has been the inability to measure these important biomarkers in serum from normal, healthy controls. Without this capability, interpretation of apparently elevated levels in problematic, and evaluation of diseased level is impossible. We have recently developed chemiluminescence ELISA (CL-ELISA), resulting in a 100-fold increase in sensitivity. To assess the influence of age, smoking, and race on serum cytokine levels in healthy population, we measured IL-4, 5, 6, 10, IFN-gamma, and GM-CSF in serum of healthy Japanese (n = 38), and Americans (n = 10) using CL-ELISA. In this small population with narrow age range, no difference between smokers and nonsmokers was found for any cytokine. No correlations between age and cytokines was demonstrated. However, Japanese samples had lower levels of IL-4, 5, and 10 than American samples. Further evaluation using more controlled study design and larger populations will be necessary to determine whether this difference is due to inherent racial differences in Th2 cell function.

A murine model for assessing the respiratory hypersensitivity potential of chemical allergens

Using equimolar quantities of 2 chemical allergens, toluene diisocyanate (TDI), noted for its ability to cause respiratory hypersensitivity, and dinitrochlorobenzene (DNCB), noted for its dermal sensitizing activity, the mouse was evaluated as a possible model to indicate respiratory hypersensitivity. A previously published procedure (Garssen et al. (1989) Immunology 68, 51-58) was followed whereby chemicals were applied epicutaneously to the shaved flank of BALB/c mice. Eight days later, animals were challenged by intranasal application of the chemical. The lungs were evaluated at 48 h. Both TDI and DNCB elicited mild mononuclear inflammatory cuffing around pulmonary vasculature. No reaction was noted around pulmonary airways. Sera, drawn 48 h following the intranasal challenge with chemical allergen, were evaluated for total IgE, hapten-specific IgE and IgG, and for IL-2, IL-4, IL-5, IL-6, and interferon gamma. Animals exposed to TDI demonstrated decreased total IgE and the presence of TDI-specific IgG. Cytokine levels were unchanged in both groups. These results indicate that in this mouse model, total serum IgE and the production of hapten-specific IgG antibodies distinguished a respiratory from a contact sensitizing chemical. Further comparison of the serologic response of mice to these two classes of chemicals is required to determine if the murine model can be used to predict dermal versus respiratory sensitizing activity of chemical allergens.

The association of ambient air pollution with twice daily peak expiratory flow rate measurements in children

A stratified sample of 83 children living in Uniontown, Pennsylvania, reported twice daily peak expiratory flow rate (PEFR) measurements on 3,582 child-days during the summer of 1990. Upon arising and before retiring, each child recorded the time, three PEFR measurements, and the presence of cold, cough, or wheeze symptoms. Ambient air pollution, including particle-strong acidity, was measured separately during the day (8 a.m. to 8 p.m.) and at night. Each child's maximum PEFR for each session was expressed as the deviation from his or her mean PEFR over the study and adjusted to a standard of 300 liters/minute. The session-specific average deviation was then calculated across all of the children. A second-order autoregressive model for PEFR was developed, which included a separate intercept for evening measurements, trend, temperature, and 12-hour average air pollutant concentration weighted by the number of hours each child spent outdoors during the previous 12-hour period. The results are expressed in terms of the interquartile range for each pollutant. A 12-hour exposure to a 125-nmol/m3 increment in particle-strong acidity was associated with a -2.5 liters/minute deviation in the group mean PEFR (95% confidence interval (CI) -4.2 to -0.8) and with increased cough incidence (odds ratio (OR) = 1.6, 95% CI 1.1 to 2.4). A 30-ppb increment in ozone for 12 hours was associated with a similar deviation in PEFR levels (-2.8, 95% CI -67 to 1.1). The association between PEFR and particle-strong acidity was observed among the 60 children who were reported as symptomatic on the prior symptom questionnaire (-2.5, 95% CI -4.5 to -0.5). The authors conclude that summer occurrences of excessive acid aerosol and particulate pollution are associated with declines in peak expiratory flow rates in children.

Racial differences in serum immunoglobulin levels: relationship to cigarette smoking, T-cell subsets, and soluble interleukin-2 receptors

To investigate the influence of race, cigarette smoking, and immunologic parameters on serum immunoglobulins, we analyzed serum IgG, IgA, and IgM levels in 455 healthy adults. The study population ranged in age from 20 to 69 years, including 282 whites and 173 blacks, 181 never-smokers, 93 ex-smokers, and 181 current smokers. Race and smoking were independently associated with alterations in serum IgG levels. Blacks had significantly higher IgG levels than whites (1,587 vs. 1,209 mg/dl; P < 0.001), and never smokers had significantly higher levels than current smokers (1,426 vs. 1,287 vs. mg/dl; P < 0.001). IgA and IgM levels were unrelated to race or smoking. Serum IgG was also found to be directly related to the proportion of HLA-DR+ cells and the level of soluble interleukin-2 receptors (sIL-2R) and inversely related to the proportion of CD4+ cells. Investigation of this racial heterogeneity may provide insights into the pathogenesis of immunologic diseases that exhibit unexplained racial variation.

Factors influencing serum neopterin and beta 2-microglobulin levels in a healthy diverse population

Sera and questionnaire data from a population-based random sample of healthy adults was used to evaluate factors influencing neopterin and beta 2-microglobulin (beta 2m) values. Both neopterin and beta 2m levels increased with age and were higher among white than blacks (mean values for whites and blacks: neopterin, 5.06 vs 4.49 nmol/L; beta 2m, 1.36 vs 1.28 mg/L). Gender differences were noted for beta 2m but not neopterin values (beta 2m males vs females: 1.37 vs 1.29 mg/L). Neopterin values were lower among current smokers than among nonsmokers (4.32 vs 5.16 nmol/L) and were higher among users of antihistamines (5.46 among users vs 4.65 nmol/L among nonusers). Neopterin and beta 2m were correlated in this healthy adult population (adjusted r = 0.53, P = 0.001), yet no other interrelationships with numerous biologic markers except between beta 2m and serum-soluble interleukin-2 receptor levels (adjusted r = .41, P = 0.05) were observed. These findings provide important baseline information to consider before planning or evaluating studies utilizing neopterin or beta 2m levels.

Racial variation in serum-soluble interleukin-2 receptor levels: a population-based study of healthy smokers and nonsmokers

To investigate the influence of race and cigarette smoking on serum levels of soluble interleukin-2 receptors (sIL-2R), we studied a population-based cohort of 282 white and 173 black adults, ages 20-69 years. Serum sIL-2R concentrations in this healthy population ranged from 146 to 2623 U/ml. Whites had significantly higher sIL-2R levels than blacks (455 versus 365 U/ml; P < 0.001), and cigarette smokers had significantly higher levels than nonsmokers (508 versus 420 U/ml; P = 0.01). White smokers had the highest levels (550 U/ml); white nonsmokers and black smokers had intermediate levels (455 and 450 U/ml, respectively); and black nonsmokers had the lowest levels (365 U/ml). Smoking cessation appeared to normalize sIL-2R levels; exsmokers who had not smoked for at least 2 years had sIL-2R levels similar to those of never smokers. These data demonstrate the wide range of serum sIL-2R concentrations found in normal healthy adults and the significant influence of race and cigarette smoking. Further investigation of this natural heterogeneity may provide insights into the mechanisms underlying genetic and environmental influences on this important immunologic parameter.

Predictive value of airways hyperresponsiveness and circulating IgE for identifying types of responses to toluene diisocyanate inhalation challenge

Development of asthma after exposure to toluene diisocyanate (TDI) has been recognized in a variety of occupational settings. However, the pathogenesis of isocyanate-induced asthma remains controversial. In particular, the role of IgE in the development of TDI-induced asthma has remained uncertain. To investigate predictive factors for response to inhalation challenge with TDI, we analyzed data from 63 subjects referred for evaluation of respiratory symptoms thought to be related to TDI sensitization. All subjects underwent interview, routine phlebotomy, spirometry, methacholine challenge, and allergy skin testing prior to TDI challenge. Spirometry and methacholine challenge were repeated 1 day after TDI challenge. The cumulative dose of methacholine needed to produce a 20% decrease in FEV1 (PD20) was determined. A PD20 of 1.4 mg or more was considered normal. Subjects were challenged by exposure to 5 to 10 ppb TDI for up to 30 min in a 9 m3 exposure chamber. A positive response was a 20% or more decrease in FEV1 within 1 h (early) or beyond 1 h (late) after TDI exposure. Thirty-four subjects (54%) had a positive response, of whom 12 (35% of responders) had isolated early responses, 13 (38%) had isolated late responses, and the remainder had dual responses. Thirty-two individuals (51%) had a positive response to methacholine (AR+) prior to TDI challenge. AR+ was strongly associated with a positive TDI challenge: 23 AR+ subjects (72%) had a positive TDI challenge, compared with only 11 AR- subjects (35%) (p < 0.01). AR positivity did not predict the time of onset of TDI response.(ABSTRACT TRUNCATED AT 250 WORDS)

Thrombocytopenia in the intensive care unit

STUDY OBJECTIVE

To determine the prevalence of thrombocytopenia in an ICU and assess which factors were associated with thrombocytopenia.

DESIGN

A review of the medical records of patients admitted during 3 separate months during 1 academic year. Patients must have survived at least 12 h in the ICU.

SETTING

A medical ICU at a university hospital.

PATIENTS

General medicine patients admitted to the ICU.

INTERVENTIONS

All medical records were reviewed. During the ICU stay, daily medications, events, and platelet count were noted. All patients were followed up until death or hospital discharge. In 22 patients, including 18 who had thrombocytopenia, bone marrow aspirates were performed.

MEASUREMENTS AND RESULTS

One hundred sixty-two admissions were evaluated. Thirty-eight (23 percent) had platelet counts less than 100,000/mm3 at least once, and 17 (10 percent) patients had platelet counts less than 50,000/mm3. Several factors were associated with thrombocytopenia; however, only sepsis, use of antineoplastic chemotherapy, elevated creatinine level, or elevated bilirubin value were independent risk factors for severe thrombocytopenia. In only one patient were the bone marrow findings different from those expected by the clinical presentation. Thrombocytopenia was associated with longer hospital stay (p < 0.001) and higher mortality (p < 0.001).

CONCLUSION

Thrombocytopenia is a common occurrence in the ICU, usually due to the underlying disease, and is associated with an increased mortality.

Airway responsiveness in young black and white women

The prevalence and severity of asthma appears to be greater in blacks than in whites. To determine if racial differences in airway responsiveness may explain these findings, methacholine challenge tests from 62 black and 238 white women 20 to 35 yr of age were evaluated. Subjects served as controls for a case-control study of the relation of airway responsiveness and preterm labor. Standardized questionnaires were used to obtain information on age, obstetrical history, education, income, cigarette smoking, medication use, and respiratory illnesses and symptoms. Total serum IgE was measured using a radioimmunoassay. Methacholine challenge testing was performed on all subjects 6 wk after delivery, and the provocative dose causing a 20% decrease in FEV1 (PD20) was calculated. Black women in the study had more pregnancies and children, were younger, less well educated and more impoverished, and reported greater cigarette smoking and less medication use than did the white women. Additionally, black women had higher geometric mean serum IgE levels (blacks: 65.4 IU versus whites: 20.0 IU; p < 0.001), lower FEV1 (blacks: 2.73 +/- 0.38 SD L versus whites: 3.19 +/- 0.39 L; p < 0.001), and greater unadjusted airway responsiveness than did white women (geometric mean PD20: blacks: 28.4 mumol versus whites: 38.8 mumol; p = 0.02). After adjusting for selective demographic and smoking differences, a significant additional effect of race on mean PD20 was found. However, after adjustment for level of serum IgE and level of FEV1, racial differences were no longer apparent.(ABSTRACT TRUNCATED AT 250 WORDS)