[Undergraduate teaching in ophthalmology. Do standardized practical examinations make sense?]

BACKGROUND

University teaching in ophthalmology has tended to focus on imparting knowledge rather than practical skills. The new skills laboratory at the University Medical Center in Göttingen enables practical skills to be taught. The focus is on basic skills that could help all physicians. The learning goals set are techniques considered basic in ophthalmology that can be mastered without requiring any physician to operate major equipment.

METHODS

The design and results from four semesters of an ophthalmological objective structured clinical examination (OSCE) following students engaged in peer-teaching, as well as feedback from a student questionnaire are described.

RESULTS

Practical skills can successfully be taught and mastered within 1 week and 68-100 % of all students achieved the maximum scores in the individual tests. The OSCE and peer- eaching were well received by the students.

CONCLUSIONS

Practical skills and peer teaching fulfill student educational goals in ophthalmology and are well accepted by undergraduates.

Die subdentale Synchondrose

BACKGROUND

During development of the axis, four different ossification centers are formed. The two cranial ossification centers are demarcated from the ossification center of the vertebral corpus by a subdental synchondrosis. During further development the subdental synchondrosis--which is thought to close spontaneously--might not close completely, which leads to the necessity for differentiating synchondrotic remnants from a fracture at the base of the dens (type II according to Anderson and D'Alonzo).

RESULTS

To characterize the architecture of the axis with particular attention to the subdental synchondrosis, the axis was harvested from 36 age- and gender-matched patients covering the human aging process from adolescence to senescence. In all specimens bone mineral density (BMD) was measured by peripheral quantitative computed tomography (pQCT). Morphological analysis after undecalcified processing of all specimens revealed a persistency of the subdental synchondrosis in 87% of all patients. Histological characterization of the subdental synchondrosis showed a cartilaginous structure interspersed with focal mineralization. Furthermore, static histomorphometric analysis revealed that trabecular bone volume and cortical thickness were significantly reduced within the base of the axis as compared to the dens and the corpus, respectively.

CONCLUSION

Taken together, these results provide evidence that the base of the axis is a structurally distinct region. Besides well-recognized biomechanical aspects, these results suggest that the structure of the base of the axis might contribute to the occurrence of fractures of the axis and offer an additional explanation for the observation of nonunion after type II dens fractures.

Oestrogen synthesis in the hippocampus: role in axon outgrowth

Ovarian oestrogens have been postulated to be neuroprotective. It has also been shown that considerable amounts of oestrogens are synthesised in hippocampal neurones. In the present study, we focused on a potential role of hippocampus-derived oestradiol compared to gonad-derived oestradiol on axon outgrowth of hippocampal neurones. To address the role of hippocampus-derived oestradiol, we inhibited oestrogen synthesis by treatment of neonatal hippocampal cell cultures with letrozole, a specific aromatase inhibitor. As an alternative, we used siRNA against steroidogenic acute regulatory protein (StAR). Axon outgrowth and GAP-43 expression were significantly down-regulated in response to letrozole and in siRNA-StAR transfected cells. The effects after inhibition of oestrogen synthesis in response to letrozole and in siRNA-StAR transfected cells were reversed by oestrogen supplementation. No difference was found between ovariectomised animals, cycling animals at pro-oestrus and ovariectomised and subsequently oestradiol-treated animals. However, high pharmacological doses of oestradiol promoted axon outgrowth, which was possible to abolish by the oestrogen receptor antagonist ICI 182,780. Our results show that oestradiol-induced neurite outgrowth is very likely mediated by genomic oestrogen receptors and requires higher doses of oestradiol than physiological serum concentrations derived from the gonads.

Synaptic plasticity in the hippocampus: effects of estrogen from the gonads or hippocampus?

Different effects of estrogen on synaptic plasticity have [corrected] been reported. Here, we summarise effects of low, gonad-derived serum estrogen concentrations, of intermediate concentrations, provided by hippocampal cells, and of pharmacological doses of estrogen on synapses and spines and on the expression of synaptic proteins. No effects of low concentrations were found. To study the effects of hippocampus-derived estradiol, we inhibited hippocampal estrogen synthesis by treatment of hippocampal cell cultures with letrozole, an aromatase inhibitor. Alternatively, we used siRNA against Steroidogenic acute regulatory protein (StAR). Spines, synapses, and synaptic proteins were significantly down regulated in response to letrozole and in siRNA-StAR transfected cells. Application of high pharmacological doses of estradiol promoted only synaptophysin expression, a presynaptic protein, but did not increase the number of boutons. Our results point to an essential role of endogenous hippocampal estrogen in hippocampal synaptic plasticity rather than to a direct influence of estrogens derived from peripheral sources, such as the gonads.

A rare complication with TVT: vaginal protrusion of the tape

The authors report a rare postoperative complication of TVT. A 38-year-old woman, suffering from genuine stress incontinence, presented 3 weeks after surgery with a 1 cm protrusion of the TVT across the median vaginal scar. A fastening point on the tape and covering it with the vaginal skin was unsuccessful. Three weeks later, we found a 5 mm protrusion of the tape. At this time we decided to resect the protruding fibers but without interrupting the tape. Regular clinical checks showed good local cicatrization, and 4 weeks later the vaginal epithelium covered the tape completely and the patient no longer suffered from genuine stress incontinence.

Pathologic and clinical features of primary pulmonary extranodal marginal zone B-cell lymphoma of MALT type

We reviewed pathologic, phenotypic, and clinical features of extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) type primarily involving lung to address unresolved questions regarding behavior and pathologic features of unambiguously diagnosed pulmonary MALT lymphoma. Lung specimens from 50 patients were reviewed. Forty-one had low-grade MALT lymphoma. Nine had low-grade MALT lymphoma and diffuse large B-cell lymphoma. The patients included 32 women and 18 men with a median age of 68 years (range 34-88 years). Half of the patients were asymptomatic at the time lymphoma was diagnosed. Radiographic abnormalities were more commonly unilateral (37 patients) than bilateral (12 patients). Localized masses or nodules occurred in 39 patients. Associated autoimmune disorders (29%) and monoclonal gammopathies (43%) were common. Low-grade lymphomas formed intraparenchymal masses composed of centrocyte-like cells, plasmacytoid lymphocytes, and plasma cells that formed lymphoepithelial lesions and exhibited a lymphangitic growth pattern. Mediastinal lymph nodes were involved histologically in 44% of cases. Lymphoma-specific survival was 71.7% at 10 years, and overall survival was significantly worse than age-and gender-matched control patients. None of the following features predicted those patients who had an adverse outcome: systemic symptoms, presence of autoimmune disorders or paraproteinemia, anatomic distribution and number of pulmonary lesions, lymph node involvement, or presence of anthracycline-treated large B-cell lymphoma.

Functional Evaluation of Plasmin Formation in Primary Breast Cancer

PURPOSE: Plasmin generation is controlled by the plasminogen activators (PA)/plasmin system, which comprises proteases (urokinase-type PA [uPA] and tissue-type PA [tPA]) and antiproteases (PA inhibitors, PAI-1 and PAI-2). The tumoral content of uPA and PAI-1 has been shown to carry prognostic value in breast cancer; however, because most assays used so far have relied on immunometric determinations, we have explored the enzymatic activities governing plasmin formation in breast cancer specimens.

PATIENTS AND METHODS: We applied semiquantitative histochemical zymography to 201 primary breast cancer tissue sections. Enzymatic activities were correlated with histopathologic parameters and clinical outcome. The median follow-up was 91 months.

RESULTS: A wide range of PA-mediated catalytic activities was detected. The overall survival was significantly worse for patients with tumors showing tPA in the lowest quartile of activity (P = .003). The 5-year overall survival of patients with tPA activity in the lowest quartile was 58% compared with 81% for patients with tPA value in the other three quartiles. Tumor size, axillary lymph node metastasis, histologic grade, lymphovascular infiltration, TP53 mutation, and tPA activity were all major risk factors in univariate analysis. tPA activity was an independent prognostic factor in a multivariate Cox regression model, both in the whole population (relative risk = 0.5, 95% confidence interval, 0.3 to 0.9; P = .02) and in the node-negative subgroup (relative risk = 0.2, 95% confidence interval, 0.08 to 0.6; P = .004).

CONCLUSION: By using a zymographic assay performed directly on primary tumor tissue sections, we demonstrate that reduced tPA-mediated plasmin production is an independent adverse prognostic factor in breast cancer.

Measurements of nitrogen dioxide in Greenland using Palmes diffusion tubes

Measurements of nitrogen dioxide using the Palmes diffusion tubes in Uummannaq, Aasiaat, and Nuuk. all located along the west-coast of Greenland, have demonstrated that the levels of pollution at the most heavily impacted sites are comparable to levels in much larger towns in Denmark. The highest concentrations were, in general, observed near sites influenced by car traffic (peak concentrations of up to 16 ppbv), medium concentrations were observed in the residential areas (2 6 ppbv), and very low levels were found at the background locations in the town outskirts (1-2 ppbv). Observations of nitrogen dioxide concentrations less than 0.1 ppbv at a remote site, Akia, 25 km from Nuuk, indicate that, compared to local sources, long-range transport of nitrogen dioxide is not important in western Greenland.

Pathologic features and expression of insulin-like growth factor-2 in adrenocortical neoplasms

We analyzed a series of adrenocortical neoplasms to compare the clinicopathologic features and the expression of insulin-like growth factor-2 (IGF-2) in adrenocortical adenomas and carcinomas. IGF-2 is a growth factor commonly expressed in many tumors including adrenal cortical and medullary neoplasms. Formalin-fixed paraffin-embedded tissues from 64 adrenocortical adenomas and 67 adrenocortical carcinomas were analyzed. The carcinomas were histologically graded from 1 to 4 based on mitotic activity and necrosis. Tumor weight, size, and follow-up information were obtained by chart review. Expression of IGF-2 was detected by immunohistochemistry with the avidin-biotin-peroxidase complex method and a monoclonal antibody against IGF-2. Adrenocortical carcinomas were larger (mean: 13.1 cm, 787 g) than adenomas (mean: 4.2 cm, 52 g) (p < 0.001). Inpatients with adrenocortical carcinomas, high tumor grade (3 or 4) (p = 0.01) was associated with decreased survival. Expression of IGF-2 was higher in adrenocortical carcinomas than in adenomas (p < 0.001). These results show that tumor size and weight along with expression of IGF-2 protein are useful features to assist in distinguishing between adrenocortical adenomas and carcinomas, and that high tumor grade is a predictor of survival in adrenocortical carcinomas. However, single immunohistochemical markers such as IGF-2 or single histopathologic features cannot by themselves separate adrenocortical adenomas from carcinomas, and a combination of clinical, gross, and microscopic features are needed to establish the diagnosis in difficult cases.

Mechanical methods for induction of labour

BACKGROUND

Mechanical methods were the first methods developed to ripen the cervix or to induce labour. Devices which were used include various type of catheters and of laminaria tents, introduced into the cervical canal or into the extra-amniotic space. Mechanical methods were never completely abandoned, but were substituted by pharmacological methods during recent decades. Potential advantages of mechanical methods, compared with pharmacological methods, may include simplicity of preservation, lower cost and reduction of the side effects. However, special attention should be paid to contraindications (e.g. low-lying placenta), risk of infection and maternal discomfort when inserting these devices. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology.

OBJECTIVES

To determine the effects of mechanical methods for third trimester cervical ripening or induction of labour in comparison with placebo/no treatment, prostaglandins (vaginal, intracervical, misoprostol) and oxytocin.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group Trials Register, the Cochrane Controlled Trials Register and bibliographies of relevant papers. Last searched April 2001.

SELECTION CRITERIA

The criteria for inclusion were the following: (1) clinical trials comparing mechanical methods used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods; (2) random allocation to the treatment or control group; (3) adequate or unclear method for allocation concealment; (4) violations of allocated management not sufficient to materially affect conclusions; (5) clinically meaningful outcome measures reported; (6) data available for analysis according to the random allocation; (7) missing data insufficient to materially affect the conclusions.

DATA COLLECTION AND ANALYSIS

A strategy has been developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. The initial data extraction was done centrally, and incorporated into a series of primary reviews arranged by methods of induction of labour, following a standardised methodology. The data will be extracted from the primary reviews into a series of secondary reviews, arranged by category of woman.

MAIN RESULTS

In total, 58 studies were considered; 45 studies have been included and 13 were excluded. Studies generally included women with unfavourable cervix and intact membranes. Comparing mechanical methods with placebo/no treatment, only one study with 48 participants reported on vaginal delivery not achieved in 24 hours (69% with mechanical methods versus 77% with placebo/no treatment; relative risk (RR) 0.90; 95% confidence interval (CI): 0.64-1.26). Hyperstimulation with fetal heart rate changes was not reported. The risk of caesarean section, reported in six studies including 416 women, was similar between groups (34%; RR 1.00; 95% CI: 0.76-1.30). There were no reported cases of severe neonatal and maternal morbidity. Comparing mechanical methods with vaginal PGE2, only one trial (109 women) reported on vaginal delivery not achieved in 24 hours (73% versus 42%; relative risk (RR) 1.74; 95% CI: 1.21-2.49). Compared with intracervical PGE2, only one trial (100 women) reported on vaginal delivery not achieved in 24 hours (68% versus 40%; relative risk (RR) 1.70; 95% CI: 1.15-2.51). Compared with with misoprostol, the effectiveness of mechanical methods was similar (34% versus 30%; relative risk (RR) 1.15; 95% CI: 0.80-1.66). The use of mechanical method reduced the risk of hyperstimulation with fetal heart rate changes when compared with prostaglandins: vaginal PGE2 (0% versus 6%; RR 0.14; 95% CI: 0.04-0.53), intracervical PGE2 (0% versus 1%; RR 0.21; 95% CI: 0.04-1.20) and misoprostol (4% versus 9%; RR 0.41; 95% CI: 0.20-0.87). There was no difference in the risk of caesarean section between mechanical methods and prostaglandins. Serious neonatal (three cases) and maternal morbidity (one case) were infrequently reported. When compared with oxytocin, use of mechanical methods reduced the risk of caesarean section (4 trials; 198 women; 17% versus 32%; RR 0.55; 95% CI: 0.33-0.91). The likelihood of vaginal delivery in 24 hours and of hyperstimulation with fetal heart rate changes was not reported. There were no reported cases of serious maternal morbidity and severe neonatal morbidity was not reported. These results are similar whatever specific mechanical method was used, except with extra-amniotic infusion. When comparing extra-amniotic infusion with any prostaglandins, women were more likely to not achieve vaginal delivery within 24 hours (57% versus 42%; RR 1.33; 95% CI: 1.02-1.75), the risk of caesarean section was increased (31% versus 22%; RR 1.48; 95% CI: 1.14-1.90), without a reduction of the risk of hyperstimulation.

REVIEWER'S CONCLUSIONS

There is insufficient evidence to evaluate the effectiveness, in terms of likelihood of vaginal delivery in 24 hours, of mechanical methods compared with placebo/no treatment or with prostaglandins. The risk of hyperstimulation was reduced when compared with prostaglandins (intracervical, intravaginal or misoprostol). Compared to oxytocin in women with unfavourable cervix, mechanical methods reduce the risk of caesarean section. There is no evidence to support the use of extra-amniotic infusion.

Development of a class-selective enzyme-linked immunosorbent assay for mercapturic acids in human urine

Epidemiological and toxicological studies often require the analysis of large numbers of samples for biological markers of exposure. The goal of this work was to develop a class-selective ELISA to detect groups of structurally closely related mercapturic acids with small nonpolar S-substituents. An assay was developed with strong recognition for mercapturates including S-benzylmercapturic acid (IC50 = 0.018 micromol/L), S-n-hexylmercapturic acid (IC50 = 0.021 micromol/L), S-phenylmercapturic acid (IC50 = 0.024 micromol/L), and S-cyclohexylmethylmercapturic acid (IC50 = 0.042 micromol/L). The same assay also showed weaker recognition for S-(1-hydroxynaphthal-2-yl)mercapturic acid and S-allylmercapturic acid (IC50 = 1.1 and 1.7 micromol/L, respectively). Subtle modifications to the hapten linker structure of the coating antigen proved to have a strong impact on the selectivity and the specificity of the assay. A slightly modified assay showed high recognition for S-benzylmercapturic acid (IC50 = 0.018 micromol/L) and weaker recognition for seven other mercapturic acids (IC50 = 0.021-10 micromol/L). Strong positive assay responses were detected in 12 urine samples obtained from persons with no known occupational exposure to exogenous electrophilic xenobiotics. Solid phase extraction and cross-reactivity indicated that the presumptive immunoreactive materials were similar in size and polarity to S-benzylmercapturic acid. The assay was more selective to mercapturic acids than the spectrophotometric thioether assay.

Pathologic features, proliferative activity, and cyclin D1 expression in Hurthle cell neoplasms of the thyroid

Making a histologic distinction between Hurthle cell adenomas and carcinomas sometimes may be difficult. We analyzed a series of Hurthle cell lesions to determine whether specific histologic features and expression of Ki67 and cyclin D1 could be useful in distinguishing Hurthle cell adenomas from carcinomas. Formalin-fixed, paraffin-embedded tissues from 128 Hurthle cell neoplasms, including 59 adenomas; 55 carcinomas; and 14 tumors classified as neoplasms of uncertain malignant behavior (UMB), which had equivocal capsular invasion but no vascular invasion, were analyzed for expression of Ki67 and cyclin D1 by immunostaining. The distribution of immunoreactivity for Ki67 with antibody MIB-1 was analyzed by quantifying the percentage of positive nuclei that was expressed as the labeling index. None of the patients with adenomas or UMB tumors developed recurrent or metastatic disease after a mean follow-up of 7.8 and 7.9 years, respectively. Of the 55 patients with Hurthle cell carcinoma, 19 were associated with metastatic disease, 13 of whom died with disease. No patient with a Hurthle cell carcinoma without vascular invasion developed metastatic disease. The mean tumor size for Hurthle cell carcinomas (4.8 cm) was significantly larger than that of Hurthle cell adenomas (3.1 cm) or UMB tumors (3.7 cm). No patient with a Hurthle cell tumor smaller than 3.5 cm developed metastatic disease, even when vascular invasion was present. The Ki67 labeling index in Hurthle cell carcinomas (10.0 +/- 1.2) was 3-fold higher than in Hurthle cell adenomas (3.2 +/- 0.3). The Ki67 labeling index in the UMB group was 5.0 +/- 0.7. Cyclin D1 showed diffuse nuclear staining in 1 of the 59 (1.7%) Hurthle cell adenomas, in 10 of the 55 (18%) Hurthle cell carcinomas, and in none of the UMB tumors. In summary, analyses of the cell cycle proteins Ki67 and cyclin D1 in Hurthle cell thyroid neoplasms indicate that these markers may assist in distinguishing some Hurthle cell carcinomas from adenomas. Among the Hurthle cell carcinomas, large tumor size and vascular invasion are associated with clinically aggressive tumors. Our study also suggests that Hurthle cell neoplasms with only equivocal capsular invasion and no vascular invasion should behave in a benign manner.

The percent of cores positive for cancer in prostate needle biopsy specimens is strongly predictive of tumor stage and volume at radical prostatectomy

PURPOSE

Pretreatment clinical staging of prostatic adenocarcinoma is important due to the increasing use of nonsurgical treatment options. Using multivariate analysis we assessed the predictive value of biopsy cores positive for cancer as a percent of all cores obtained as well as the percent surface area of needle cores involved with tumor for determining tumor volume and pathological stage at radical prostatectomy. Candidate variables for the multivariate model included patient age, clinical disease stage, serum prostate specific antigen (PSA) and Gleason score of cancer in the needle biopsy.

MATERIALS AND METHODS

We reviewed prostate needle biopsy findings in 207 consecutive patients who subsequently underwent radical retropubic prostatectomy. Each biopsy specimen was assessed for tumor involvement by calculating the percent of cores positive for cancer, percent surface area involved in all cores and Gleason score. Initial serum PSA and preoperative clinical disease stage were incorporated with biopsy results into a multivariate model to determine the parameters most predictive of pathological stage and tumor volume at radical retropubic prostatectomy.

RESULTS

Of the 207 patients 152 (73.4%) had organ confined cancer and 55 (26.6%) had extraprostatic extension (pathological stages T2 and T3 or greater, respectively). Preoperative clinical staging information was available in 195 cases, in which disease was clinically confined and not confined in 184 (94.4%) and 11 (5.6%), respectively. Needle biopsy revealed a surface area of cancer ranging from less than 5% in 69 patients (33.3%) to 90% (mean 16, median 10). Univariate analysis demonstrated that the risk of extraprostatic extension was predicted by preoperative serum PSA (p = 0.027), the percent of cores and percent of surface area positive for cancer (p <0.0001), and Gleason score (p = 0.0009). Clinical stage approached significance (p = 0.071). Multivariate analysis showed that the percent of positive cores (p = 0.0003), initial serum PSA (p = 0.005) and Gleason score of cancer in the needle biopsy (p = 0.03) were the only parameters that jointly predicted pathological stage (T2 versus T3). Percent of tumor surface area involvement in the needle biopsies did not add any more information after the percent of positive cores was known. Univariate analysis revealed that the percent of cores positive for cancer (Spearman r = 0.52, p <0.0001), Gleason score (Spearman r = 0.34, p <0.0001) and initial serum PSA (Spearman r = 0.24, p = 0.003) were predictive of log tumor volume at radical prostatectomy, while clinical stage was not (rank sum test p = 0.14). On multivariate analysis the percent of positive cores (p <0.0001), Gleason score (p <0.0001) and initial serum PSA (0.0033) were the only variables that jointly were predictive of tumor volume.

CONCLUSIONS

The percent of needle biopsy cores and surface area positive for cancer are the strongest predictors of pathological stage and tumor volume on multivariate analysis incorporating preoperative serum PSA and Gleason score.

An air pollution model for use in epidemiological studies: evaluation with measured levels of nitrogen dioxide and benzene

The aim of the study was to evaluate the predictions derived from the Danish Operational Street Pollution Model (OSPM) when the input data are obtained by simple methods that could be used in large-scale epidemiological studies. The model calculations were thus compared with passive sampler measurements of nitrogen dioxide and benzene at 103 street locations in Copenhagen, Denmark, and at 101 locations in rural areas. Data on traffic and street configuration were collected by means of a simple registration scheme in which forms were filled out by local municipal authorities. Meteorological data were derived from routine measurements at Copenhagen airport, and data on background air pollution were based on a simple empirical model. Differences in air pollution levels between rural areas and Copenhagen and differences in nitrogen dioxide concentrations at various locations in Copenhagen were well reproduced by the OSPM. The correlation coefficients (r) between the measured and the predicted half-year average concentrations of nitrogen dioxide in Copenhagen were between 0.75 and 0.80 for various degrees of precision of the input data for the model. The results indicate that the OSPM used with the presented methods for generation of input data might be useful in assessing long-term exposure to air pollutants in epidemiological studies.

Ambient air levels and the exposure of children to benzene, toluene, and xylenes in Denmark

The aims of the study were to evaluate if the front-door concentrations of benzene, toluene, and xylenes can be used to classify the personal exposures of Danish children and to identify factors that affect their personal exposure. Average concentrations were measured over 1 week with diffusive samplers, and the personal exposures of 98 children and the concentrations outside the front doors of their homes were measured simultaneously. Time and activity patterns were noted in diaries. The front-door concentrations were significantly higher in Copenhagen than in rural areas (all P < 0.0001), but the personal exposures were only slightly higher. Even though the personal exposures were highly significantly associated with front-door concentrations in urban areas (all P < 0.004), use of the residential front-door concentration as an exposure surrogate would imply misclassification, as it cannot be used for rural children. Multiple regression analyses brought to light several factors that affect the exposure of children independently, including front-door concentration, riding in cars, and activities involving potential exposure to gasoline vapors like motocross, moped driving, and refueling of cars.

Front-door concentrations and personal exposures of Danish children to nitrogen dioxide

The aims of the study were to evaluate the front-door concentration of traffic exhaust fumes as a surrogate for the personal exposure of children and to study factors in the behavior and the environment of children that affect their personal exposure to nitrogen dioxide (NO(2)). The exposure to NO(2) of 103 children living in Copenhagen and 101 children living in rural areas of Denmark was studied by measuring average concentrations over 1 week with diffusive badge samplers placed outside the front door of the home, inside the child's bedroom, and on each child. Detailed information about the activities of the children involving potential exposure to NO(2) was noted in diaries. The results indicated that the front-door concentration of traffic pollution might be used to classify the personal exposure of urban children, although misclassification would be introduced. Multiple regression analysis showed several factors that affected the personal NO(2) exposure of the children independently, including the front-door concentration, the bedroom concentration, time spent outdoors, gas appliances used at home, passive smoking, and burning candles.

Exposure of Danish children to traffic exhaust fumes

This exposure study addresses the validity of the exposure assessment method of an epidemiological study of traffic-related air pollution and childhood cancer. In particular, this paper concerns the question of whether the concentration of nitrogen dioxide (NO2) outside the front door is a valid marker of the exposure of the child living at the address. The study includes 100 children living on streets with dense traffic in central parts of Copenhagen and 100 children living in rural areas. Preliminary results, based on 25% of the study subjects, suggest that both the outdoor NO2-concentration and the exposure of the children are two to three times higher in Copenhagen than in the rural districts. Moreover, the results suggest that the NO2-concentration outside the front door is a poor marker of the exposure of the children in Copenhagen, but a marker of some relevance for the exposure of the children in rural districts. The preliminary results must be treated with caution, as among other things, the analysis did not consider seasonal changes and indoor NO2-sources such as passive smoking, candles, and gas appliances.

Mutagenicity and chemical analysis of airborne particulates from a rural area in Italy

Mutagenic activities of a sample of characterized airborne particulates collected in a rural location near Ispra (Italy) during the summer of 1980 were detected by the Ames test using TA 1537, TA 1538, TA 98, and TA 100 Salmonella strains. Eight chemical classes fractionated from the CH2Cl2 extract of the particulates were bioassayed, and their mutagenicities (TA 98 plus S9) were as follows: organic bases I greater than polar neutrals greater than insolubles in cyclohexane greater than organic acid II greater than aerosol "in toto" greater than intermediate neutrals greater than polycyclic aromatic hydrocarbons greater than organic acids I greater than nonpolar neutrals. Periodical samples were taken in the same location from March to December 1981, extracted in dimethyl sulfoxide (DMSO), and directly tested with TA 1537, TA 98, and TA 100 Salmonella strains. For all the strains the mutagenicity varied markedly according to the season, the cold-month samples being much more mutagenic than the summer-month samples. The additional of S9 increased the mutagenicity (twofold) of the cold-month samples. The higher mutagenicity of the samples collected during the cold months could be due to greater amounts of mutagens produced by the combustion processes of domestic heating.