Modeling the intraurban variability of ambient traffic pollution in Toronto, Canada

The objective of this paper is to model determinants of intraurban variation in ambient concentrations of nitrogen dioxide (NO2) in Toronto, Canada, with a land use regression (LUR) model. Although researchers have conducted similar studies in Europe, this work represents the first attempt in a North American setting to characterize variation in traffic pollution through the LUR method. NO2 samples were collected over 2 wk using duplicate two-sided Ogawa passive diffusion samplers at 95 locations across Toronto. Independent variables employed in subsequent regression models as predictors of NO2 were derived by the Arc 8 geographic information system (GIS). Some 85 indicators of land use, traffic, population density, and physical geography were tested. The final regression model yielded a coefficient of determination (R2) of .69. For the traffic variables, density of 24-h traffic counts and road measures display positive associations. For the land use variables, industrial land use and counts of dwellings within 2000 m of the monitoring location were positively associated with NO2. Locations up to 1500 m downwind of major expressways had elevated NO2 levels. The results suggest that a good predictive surface can be derived for North American cities with the LUR method. The predictive maps from the LUR appear to capture small-area variation in NO2 concentrations. These small-area variations in traffic pollution are probably important to the exposure experience of the population and may detect health effects that would have gone unnoticed with other exposure estimates.

Multiplexed fluorescent bead-based immunoassays for quantitation of human cytokines in serum and culture supernatants

BACKGROUND

An increasing volume of data suggests a relationship between cytokine levels in human body fluids and disease pathogenesis. Traditionally, many individual assays would be performed to measure the large number of known cytokines and determine their associations with disease. A new technique for the simultaneous measurement of multiple cytokines in cell culture supernatants by fluorescent microsphere-based flow cytometry was adapted to human sera.

METHODS

Multiplexed sandwich immunoassays for eight cytokines were developed by coupling cytokine-specific capture antibodies to beads with different emission spectra. The binding of biotinylated detection antibodies bound with a streptavidin-conjugated fluorochrome was analyzed. Recovery of "spiked" cytokines, sensitivity, and variability of the assays were evaluated. In addition, the results of the bead assays were compared with the results of commercial enzyme-linked immunosorbent assays (ELISAs) that used the same antibody pairs.

RESULTS

Correlations of the bead assays and the ELISAs were 0.974 (n = 18) for supernatant samples and 0.859 (n = 28) for serum samples. High, false-positive values observed with some sera, assumed to be produced by heterophilic antibodies, were reduced by preincubation with a cocktail of animal sera.

CONCLUSIONS

Fluorescent bead-based immunoassays can be used to quantitate multiple cytokines in human sera and contribute to an understanding of the role of cytokines in disease processes. This methodology is applicable to many combinations of purified analytes and high-affinity antibodies. Published 2001 Wiley-Liss, Inc.

Vein adaptation to arterialization in an experimental model

PURPOSE

The events preceding myointimal thickening in vein grafts after vascular reconstructions are not well characterized. Indeed, the injury response associated with vein graft arterialization may be different than that observed in the balloon angioplasty model. Therefore, we used a rat model to study the early cellular response after arterialization of vein grafts.

METHODS

Epigastric veins were placed as femoral artery interposition grafts in 37 male Lewis rats (weight range, 350-400 g). Vein grafts and contralateral epigastric veins were harvested at different time points (6 hours, 1 day, 2 days, 3 days, 7 days, 14 days, 21 days, 30 days, and 70 days). Tissue specimens were processed for histology and immunohistochemistry with antibodies for the proliferating cell nuclear antigen (PCNA) and for different cell types. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay was used as a means of determining the presence of apoptosis. Electron microscopy was used as means of assessing the integrity of the endothelial cell surface (SEM) and confirming the presence of apoptosis (TEM). Specimens were also snap frozen in liquid nitrogen for RNA isolation and molecular analysis.

RESULTS

At 1 day, endothelial denudation with platelet deposition on the surface was shown by means of SEM. Both apoptosis and necrosis of smooth muscle cells (SMCs) were present in the media, along with monocyte infiltration. Cellular proliferation and apoptosis were most intense within the first week of implantation. PCNA staining was first seen in the adventitial fibroblasts and microvessels, then in the medial SMCs at 3 days. With reverse transcriptase polymerase chain reaction, upregulation of vascular endothelial growth factor (VEGF) messenger RNA (mRNA) was noted at 1 day. Myointimal thickening progressively developed, with no apparent diminution of the luminal area as long as 70 days after implantation. By means of the analysis of the transforming growth factor beta1, mRNA showed expression during intimal thickening and accumulation of extracellular matrix. Reendothelialization was complete at 30 days.

CONCLUSIONS

These observations indicate that the cellular composition in our vein graft model is similar to human stenotic explants. Endothelial denudation is observed in rat vein grafts with complete regeneration by 30 days. VEGF mRNA is upregulated at 1 day, followed by proliferation of microvessel endothelial cells in the adventitia. Cellular proliferation and apoptosis are minimal after 21 days, with progressive intimal thickening likely to be the result of matrix accumulation.

Progression of influenza viral infection through the murine respiratory tract: the protective role of sleep deprivation

Sleep deprivation is reported to have both beneficial and harmful effects upon host defenses. In the work reported herein, we address the effects of sleep deprivation on the mucosal anti-influenza defenses of both immune and nonimmune BALB/c mice. Sleep deprivation does not depress existing mucosal antiviral defenses in the respiratory tracts of BALB/c mice; in fact, it may actually be beneficial. Nasal mucosal immunity is not adversely affected in immune mice by sleep deprivation. In nonimmune mice, sleep deprivation slows or prevents the progress of nasal influenza viral infection down the trachea into the lungs. By 72 hours post-infection, 12 of 12 control mice shed virus into bronchioalveolar lavages (BAL) while only 2 of 12 sleep deprived mice shed virus (p<0.001). BAL levels of IL-1beta and interferon alpha were increased in sleep deprived animals, suggesting that sleep deprivation may exert its beneficial effects on the respiratory tract by upregulating the production of antiviral cytokines.

Interleukin-6, C-reactive protein, and abnormal cardiorespiratory responses to immunization in premature infants

OBJECTIVE

We report our experience with routine immunization of 89 premature infants in the neonatal intensive care unit because 1) a substantial number of them developed abnormal clinical signs, and 2) all but one of those who received diphtheria, tetanus, and whole-cell pertussis (DTwP) vaccine responded with elevations of interleukin-6 (IL-6) and C-reactive protein (CRP) concentrations that are otherwise characteristic of bacterial disease.

METHODOLOGY

We hypothesized that the elevated IL-6 and CRP levels were solely a response to immunization and that treatment with antibiotics was not necessary. We performed this study in two consecutive parts. In part 1, we prospectively evaluated 79 consecutive premature infants who were immunized with DTwP, Haemophilus b conjugate vaccine, hepatitis B vaccine, and inactivated polio vaccine, (Hib, HBV, and IPV). IL-6 and CRP were determined before immunization and every 12 hours on three occasions after immunization. In part 2, we studied an additional 10 infants who received acellular pertussis vaccine (DTaP) and who, 2 days later, received Hib, HBV, and IPV immunization simultaneously. We followed the same schedule of IL-6 and CRP determinations as in part 1.

RESULTS

In part 1, 24 infants (30%) developed abnormal cardiorespiratory signs within 24 hours after immunization. CRP and IL-6 values rose to abnormal levels after immunization in all but one infant; that infant was later shown to have a T-cell abnormality. In part 2, 3 infants had abnormal cardiorespiratory signs after simultaneous immunization with Hib, HBV, and IPV, but not after DTaP. IL-6 and CRP levels remained normal in all 10 infants.

CONCLUSIONS

Part 1 demonstrates clearly the temporal relationship between IL-6 and CRP increments after DTwP, Hib, HBV, and IPV vaccines. In part 2 (DTaP was substituted for DTwP), there were no elevations of IL-6 or CRP, thus indicating that whole-cell pertussis component of DTwP was responsible for IL-6 and CRP elevations. Abnormal cardiorespiratory signs occurred frequently after immunizations in part 1, but they were unrelated to the magnitude of IL-6 and CRP elevations. The frequency of cardiorespiratory difficulty and its occasional severity suggest a need to monitor premature infants for approximately 48 hours after routine immunization.

OMA-AML-1: a leukemic myeloid cell line with CD34+ progenitor and CD15+ spontaneously differentiating cell compartments

OMA-AML-1 was established from a patient with acute myelomonocytic (M4) leukemia at fifth relapse when blasts were greater than 85% CD34+, CD15-. Leukemic cells were established in suspension culture and independently grown as subcutaneous tumors in SCID mice. Cells growing in suspension culture underwent differentiation by phenotypic and morphologic criteria. In contrast, cells grown as subcutaneous solid tumors in SCID mice maintained progenitor cell characteristics with high-density CD34 expression and lack of morphologic differentiation. A tendency toward differentiation to CD15+, CD34- cells in vitro and self-renewal of CD34+, CD15- cells in vivo was consistently demonstrated regardless of whether cells were initially grown in vitro or in vivo. The cell line maintains both a CD34+, CD15- progentitor cell pool and a non-overlapping, CD15+, CD34- differentiating cell compartment after more than 1 year in continuous culture. Cell cycle analysis and cloning experiments were consistent with terminal differentiation occurring in the CD15+, CD34- population. The cell line shows concentration-dependent proliferative responses to interleukin (IL)-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-6, but not to granulocyte CSF (G-CSF). OMA-AML-1 appears to mimic several features of normal myeloid hematopoiesis and should prove useful for the study of normal and malignant myeloid differentiation.

Binding of antisense phosphorothioate oligonucleotides to murine lymphocytes is lineage specific and inducible

A phosphorothioate oligonucleotide that has been employed to inhibit HIV-1 viral expression in chronically infected H9 cells was examined for its ability to associate with murine lymphoid cells. The relationship between cellular oligonucleotide concentration and the lymphoid target tissues is important to the selection of an animal model, evaluation of potential side effects, and understanding the actions of a therapeutically useful antisense oligonucleotide. Lymphoid cells were harvested from murine peripheral blood, bone marrow, thymus, lymph node, and spleen. Cell subpopulations that bind the oligonucleotide were distinguished by two-color flow cytometry employing a fluorescein-labeled anti-rev oligonucleotide and phycoerythrin-labeled antibodies to selected cell surface molecules associated with unique subpopulations of cells. Very little oligonucleotide binding was observed in peripheral blood mononuclear cells or thymic T cells, but substantial numbers of cells, primarily B cells from bone marrow and spleen, accumulated the oligonucleotide. The cell-associated oligonucleotide was increased significantly in lymphoid populations when the cells were mitogen pretreated with either concanavalin-A (ConA), a T cell mitogen, or lipopolysaccharide (LPS), a B cell mitogen. These data clearly demonstrate the ability of fluorescein-conjugated oligonucleotides to bind to unique cell populations in suspension, allowing simultaneous two-color phenotypic analysis, suggesting that fluorescein-conjugated oligonucleotides may be a useful bridge between in vitro molecular biology techniques and in vivo cell biology. In addition, these data provide optimism concerning the in vivo treatment of chronically infected HIV patients using antisense oligonucleotides.

Pathogenesis and significance of urogenital mycoplasmal infections

U. urealyticum and M. hominis can no longer be considered as harmless commensals of the lower genitourinary tract. Both can produce disease in humans. Diagnosis and management of infections due to these organisms must be based upon isolation of the organisms from the affected site and preferably the number of organisms present. Due to the frequent resistance of both organisms to tetracycline, treatment must be based upon appropriate antibiotic sensitivities. For a more detailed description of the basic biology of these organisms and isolation and identification and treatment, the reader is referred to several recent reviews.

Patterns of Schistosoma haematobium egg distribution in the human lower urinary tract. II. Obstructive uropathy

In a series of 32 unselected consecutive autopsies of Egyptian male adults, we found a significant prevalence of schistosomal obstructive uropathy (SOU) and of precursor lesions of stenosis, fibrosis and induration of the ureters (62.5%). Lower urinary tracts with obstructive uropathy had a significantly higher total egg burden (TEB) than did lower urinary tracts with any other type of gross lesion (i.e., benign prostatic hypertrophy, other urethral outlet obstruction, or SOU precursor lesions). In turn, lower urinary tracts with any type of gross change had higher egg burdens than did tracts which appeared grossly normal. Lower urinary tracts with any type of gross lesion had significantly larger seminal vesicles than did tracts which were grossly normal. Moreover, relative weight of seminal vesicles could be correlated with the S. haematobium egg burdens in the seminal vesicles. In a series of lower urinary tracts taken from unselected consecutive American autopsies, seminal vesicle weight could be correlated with increase in prostatic weight in those tracts with prostatic hypertrophy; the same correlation could not be found in tracts without prostatic hypertrophy. Thus, seminal vesicle hypertrophy appears to correlate with obstructive uropathy in general, not solely obstructive uropathy of schistosomal origin. Digital evaluation of seminal vesicle size may be useful in the clinical evaluation of such patients.

Patterns of Schistosoma haematobium egg distribution in the human lower urinary tract. I. Noncancerous lower urinary tracts

Schistosoma haematobium egg burdens (eggs/g of tissue) of 17 anatomic segments of lower urinary tracts from 32 unselected Egyptian autopsies have been determined by tissue digestion and replicate counts of aliquots of the digestate. There were three anatomic patterns of egg distribution in these lower urinary tracts: apical, basal and diffuse. Regression of egg burdens of each of the anatomic segments as the dependent variable against egg burdens of the entire lower urinary burden yielded a good fit for 15 of 17 of these segments. Statistical analyses revealed that many of these equations for discrete anatomic segments can be combined, generally giving one equation for anatomic regions which are in continuity, indicating that the female worm lives and oviposits in specified venous plexes. These equations also suggest that there are differences in the rates, duration and onset of egg accumulation which may be responsible for schistosomal obstructive uropathy as a cause of death in fairly young individuals.

Patterns of Schistosoma haematobium egg distribution in the human lower urinary tract. III. Cancerous lower urinary tracts

The distribution of S. haematobium eggs in urinary bladders containing tumors and removed at surgery has been studied; the majority of these tumors are well differentiated squamous cell carcinomas. The same three anatomic patterns of egg accumulation described in part I of this series (noncancerous lower urinary tracts) were found in these cancerous bladders, but, in addition, most of the tumors were surrounded by a collar of heavy S. haematobium egg deposition. The egg burdens in these collars were, on the average, twice the average egg burden in the remainder of the urinary bladder. These collars do not seem to be artifacts created by growth of the tumor and subsequent displacement of the adjacent normal tissue, creating a region of heavy egg concentrations; rather, these heavy S. haematobium egg concentrations seem to act as promoters of urothelial carcinogenesis.