Prognostic significance of beat-to-beat variability of spatial heterogeneity of repolarization analyzed from a 5-minute resting electrocardiogram in coronary artery disease.

BACKGROUND: Data on the prognostic significance of temporal variability of spatial heterogeneity of electrocardiographic repolarization in coronary artery disease (CAD) are limited. OBJECTIVE: The purpose of this study was to evaluate the prognostic value of temporal variability of T-wave morphology analyzed from a 5-minute resting electrocardiogram in CAD. METHODS: The standard deviation (SD) of T-wave morphology dispersion (TMD-SD) and the SD of total cosine R-to-T were analyzed on a beat-to-beat basis from a 5-minute period of the standard resting 12-lead electrocardiogram obtained before the clinical stress test in 1702 patients with angiographically verified CAD and well-preserved left ventricular function. RESULTS: During an average of 8.7 ± 2.2 years of follow-up, 60 patients experienced sudden cardiac death/arrest (SCD/SCA) (3.5%), 69 patients nonsudden cardiac death (NSCD) (4.1%), and 161 patients noncardiac death (9.5%). TMD-SD was significantly higher in patients who experienced SCD/SCA than in other patients (1.72 ± 2.00 vs 1.12 ± 1.75; P = .01) and higher in patients who succumbed to NSCD than in other patients (1.57 ± 1.74 vs 1.12 ± 1.76; P = .04), but it did not differ significantly between patients who experienced noncardiac death and those without such an event (1.16 ± 1.42 vs 1.14 ± 1.79; P = .86). In the Cox multivariable hazards model, TMD-SD retained its significant association with the risk of SCD/SCA (hazard ratio 1.119; 95% confidence interval 1.015-1.233; P = .024) but not with the risk of NSCD (hazard ratio 1.089; 95% confidence interval 0.983-1.206; P = .103). CONCLUSION: TMD-SD is independently associated with the long-term risk of SCD/SCA in patients with CAD.

Day-of-the-week variation of sudden unexpected cardiac death.

Background: There has been some controversy about the day-of-the-week (septadian) variation of unexpected sudden cardiac death (SCD). Methods: We evaluated the incidence of unexpected SCD on different days of the week in a consecutive series of 5869 SCD victims from Northern Finland [the FINGESTURE study (Finnish Genetic Study of Arrhythmic Events)]. As it is mandatory in Finland, a medico-legal autopsy was performed on all unexpected sudden death victims. The autopsies were performed between the years 1998-2017. Results: The mean incidence of unexpected SCD was higher at weekends (during the days from Friday to Sunday, peaking on Saturday) than during the days from Monday to Thursday (8.54 ± 0.72 vs. 7.22 ± 0.19 SCDs per day of the week per 100,000 inhabitants per year, p < 0.001). Regardless of sex or ischemic versus non-ischemic etiology of SCD, the distribution of the occurrence of SCD among the days of the week was similar compared with the whole SCD cohort. Conclusion: The incidence of unexpected SCD was highest at weekends (during the days from Friday to Sunday, peaking on Saturday).

Holocene sea ice variability driven by wind and polynya efficiency in the Ross Sea.

The causes of the recent increase in Antarctic sea ice extent, characterised by large regional contrasts and decadal variations, remain unclear. In the Ross Sea, where such a sea ice increase is reported, 50% of the sea ice is produced within wind-sustained latent-heat polynyas. Combining information from marine diatom records and sea salt sodium and water isotope ice core records, we here document contrasting patterns in sea ice variations between coastal and open sea areas in Western Ross Sea over the current interglacial period. Since about 3600 years before present, an increase in the efficiency of regional latent-heat polynyas resulted in more coastal sea ice, while sea ice extent decreased overall. These past changes coincide with remarkable optima or minima in the abundances of penguins, silverfish and seal remains, confirming the high sensitivity of marine ecosystems to environmental and especially coastal sea ice conditions.

Prominent features in isotopic, chemical and dust stratigraphies from coastal East Antarctic ice sheet (Eastern Wilkes Land).

In this work we present the isotopic, chemical and dust stratigraphies of two snow pits sampled in 2013/14 at GV7 (coastal East Antarctica: 70°41' S - 158°51' E, 1950 m a.s.l.). A large number of chemical species are measured aiming to study their potentiality as environmental changes markers. Seasonal cluster backward trajectories analysis was performed and compared with chemical marker stratigraphies. Sea spray aerosol is delivered to the sampling site together with snow precipitation especially in autumn-winter by air masses arising from Western Pacific Ocean sector. Dust show maximum concentration in spring when the air masses arising from Ross Sea sector mobilize mineral dust from ice-free areas of the Transantarctic mountains. The clear seasonal pattern of sulfur oxidized compounds allows the dating of the snow-pit and the calculation of the mean accumulation rate, which is 242 ± 71 mm w.e. for the period 2008-2013. Methanesulfonic acid and NO3- do not show any concentration decreasing trend as depth increases, also considering a 12 m firn core record. Therefore these two compounds are not affected by post-depositional processes at this site and can be considered reliable markers for past environmental changes reconstruction. The rBC snow-pit record shows the highest values in summer 2012 likely related to large biomass burning even occurred in Australia in this summer. The undisturbed accumulation rate for this site is demonstrated by the agreement between the chemical stratigraphies and the annual accumulation rate of the two snow-pits analysed in Italian and Korean laboratories.

Sea salt sodium record from Talos Dome (East Antarctica) as a potential proxy of the Antarctic past sea ice extent.

Antarctic sea ice has shown an increasing trend in recent decades, but with strong regional differences from one sector to another of the Southern Ocean. The Ross Sea and the Indian sectors have seen an increase in sea ice during the satellite era (1979 onwards). Here we present a record of ssNa+ flux in the Talos Dome region during a 25-year period spanning from 1979 to 2003, showing that this marker could be used as a potential proxy for reconstructing the sea ice extent in the Ross Sea and Western Pacific Ocean at least for recent decades. After finding a positive relationship between the maxima in sea ice extent for a 25-year period, we used this relationship in the TALDICE record in order to reconstruct the sea ice conditions over the 20th century. Our tentative reconstruction highlighted a decline in the sea ice extent (SIE) starting in the 1950s and pointed out a higher variability of SIE starting from the 1960s and that the largest sea ice extents of the last century occurred during the 1990s.

Multi-year record of atmospheric and snow surface nitrate in the central Antarctic plateau.

Continuous all year-round samplings of atmospheric aerosol and surface snow at high (daily to 4-day) resolution were carried out at Dome C since 2004-05 to 2013 and nitrate records are here presented. Basing on a larger statistical data set than previous studies, results confirm that nitrate seasonal pattern is characterized by maxima during austral summer for both aerosol and surface snow, occurring in-phase with solar UV irradiance. This temporal pattern is likely due to a combination of nitrate sources and post-depositional processes whose intensity usually enhances during the summer. Moreover, it should be noted that a case study of the synoptic conditions, which took place during a major nitrate event, showed the occurrence of a stratosphere-troposphere exchange. The sampling of both matrices at the same time with high resolution allowed the detection of a an about one-month long recurring lag of summer maxima in snow with respect to aerosol. This result can be explained by deposition and post-deposition processes occurring at the atmosphere-snow interface, such as a net uptake of gaseous nitric acid and a replenishment of the uppermost surface layers driven by a larger temperature gradient in summer. This hypothesis was preliminarily tested by a comparison with surface layers temperature data in the 2012-13 period. The analysis of the relationship between the nitrate concentration in the gas phase and total nitrate obtained at Dome C (2012-13) showed the major role of gaseous HNO3 to the total nitrate budget suggesting the need to further investigate the gas-to-particle conversion processes.

The Laschamp geomagnetic excursion featured in nitrate record from EPICA-Dome C ice core.

Here we present the first direct comparison of cosmogenic (10)Be and chemical species in the period of 38-45.5 kyr BP spanning the Laschamp geomagnetic excursion from the EPICA-Dome C ice core. A principal component analysis (PCA) allowed to group different components as a function of the main sources, transport and deposition processes affecting the atmospheric aerosol at Dome C. Moreover, a wavelet analysis highlighted the high coherence and in-phase relationship between (10)Be and nitrate at this time. The evident preferential association of (10)Be with nitrate rather than with other chemical species was ascribed to the presence of a distinct source, here labelled as "cosmogenic". Both the PCA and wavelet analyses ruled out a significant role of calcium in driving the (10)Be and nitrate relationship, which is particularly relevant for a plateau site such as Dome C, especially in the glacial period during which the Laschamp excursion took place. The evidence that the nitrate record from the EDC ice core is able to capture the Laschamp event hints toward the possibility of using this marker for studying galactic cosmic ray flux variations and thus also major geomagnetic field excursions at pluri-centennial-millennial time scales, thus opening up new perspectives in paleoclimatic studies.

Note: An analyzer for field detection of H2S by using cavity ring-down at 1.57 µm.

A prototype analyzer for the detection of hydrogen sulfide (H2S), based on cavity ring-down spectroscopy, is described. The device exploits, whenever possible, optical fibers, in order to simplify the alignment and to improve the stability. A trade-off between low detection level and simplicity has been pursued. The experimental results obtained during tests on different kinds of H2S samples are shown.

Preparation of small size palladium nanoparticles by picosecond laser ablation and control of metal concentration in the colloid.

We assessed a method for the preparation of small, highly stable and unprotected Pd nanoparticles by picosecond laser ablation in 2-propanol. The nanoparticles can be extracted from 2-propanol by centrifugation and redispersed in water, where a strongly negative ζ-potential assures long term stability. The proposed procedure permits reduction of particle size down to 1.6nm and optimization of the Pd(0):Pd(II) ratio which, in the best cases, was of the order of 6:1. The increase of this ratio with ablation times has been correlated to the high temperature conversion of PdO to metallic Pd by a simple theoretical model. A study of the relationship between colloid absorption at 400nm and Pd concentration permitted the role of PdO in the determination of the UV-vis spectra to be clarified and the limits of the Mie theory for the evaluation of colloid concentration to be established. The absorption at 400nm can be used as a fast method to estimate the Pd content in the colloids, provided that a calibration of the ablation process is preliminarily performed.

Selecting an appropriate biomonitoring strategy to evaluate dermal exposure to opioid narcotic analgesics in pharmaceutical production workers.

OBJECTIVES: In a follow-up study of previous research, in which exposure pathways for opioid narcotic analgesics were identified in pharmaceutical workers involved in drug synthesis, the current research focused on the selection of an appropriate biomonitoring strategy. METHODS: Six opioid narcotic production workers were intensively monitored during a (1 week) fentanyl production campaign. A systematic sampling scheme was followed that provided information about hand contamination and biomarker levels at multiple time points. RESULTS: Linear mixed-effects models, incorporating half-shift and end-of-shift hand contamination levels, showed a positive and significant correlation with fentanyl urinary excretion occurring at many of the 4 h time lags investigated (4-28 h). Optimum model characteristics, including both minimal between- and within-worker variability, were obtained at lag times of 24 h and 20 h, respectively, advocating a pre-shift urine sampling strategy on the following day. In addition, for these lag times the portion of the variability explained by the model was maximal. Furthermore, using a distributed lag model, it was demonstrated that urinary fentanyl levels were positively correlated with hand contamination levels measured at the preceding four 8 h time lags (8-32 h), although statistical significance was only shown for a lag time of 24 h. CONCLUSION: Fentanyl levels in pre-shift urine samples reflect dermal exposure to the compound during the previous day. Thus, in the specific working environment investigated, a biological monitoring protocol evaluating pre-shift urinary fentanyl levels could provide an adequate risk estimate in individual workers.

Ultra-sensitive Flow Injection Analysis (FIA) determination of calcium in ice cores at ppt level.

A Flow Injection Analysis (FIA) spectrofluorimetric method for calcium determination in ice cores was optimised in order to achieve better analytical performances which would make it suitable for reliable calcium measurements at ppt level. The method here optimised is based on the formation of a fluorescent compound between Ca and Quin-2 in buffered environment. A careful evaluation of operative parameters (reagent concentration, buffer composition and concentration, pH), influence of interfering species possibly present in real samples and potential favourable effect of surfactant addition was carried out. The obtained detection limit is around 15 ppt, which is one order of magnitude lower than the most sensitive Flow Analysis method for Ca determination currently available in literature and reproducibility is better than 4% for Ca concentrations of 0.2 ppb. The method was validated through measurements performed in parallel with Ion Chromatography on 200 samples from an alpine ice core (Lys Glacier) revealing an excellent fit between the two chemical series. Calcium stratigraphy in Lys ice core was discussed in terms of seasonal pattern and occurrence of Saharan dust events.

O efeito do estrógeno nas reservas glicogênicas de musculoesqueléticos desnervados de ratas / The estrogen effect on glycogen reserves of denervated skeletal muscles of female rats

OBJETIVO: Avaliar o efeito muscular do estrógeno em ratas submetidas à desnervação de membro posterior. MÉTODO: Ratas Wistar foram divididas em 5 grupos (n=6): Controle, Desnervado 7 dias, Desnervado 15 dias, Desnervado tratado com estrógeno (200æg/rato, via subcutânea, diariamente) durante 7 dias e Desnervado tratado com estrógeno durante 15 dias. Após os períodos experimentais, foi realizada a avaliação de glicogênio (GLI) dos músculos sóleo (S), gastrocnêmio branco (GB) e vermelho (GV), além da avaliação do peso do sóleo. A análise estatística foi feita através do teste de normalidade, ANOVA e teste de Tukey (p<0,05). RESULTADOS: A desnervação promoveu redução (p<0,05) no GLI no período de 7 (S: 44 por cento, GB: 32 por cento; GV: 32 por cento) e de 15 dias (S: 62 por cento, GB: 44 por cento; GV: 53 por cento), além da redução do peso do S (7 dias: 29,7 por cento; 15 dias: 36,6 por cento) . Porém, o tratamento com estrógeno promoveu elevação (p<0,05) no GLI, nessa condição, tanto durante 7 dias (S: 19 por cento; GB: 60 por cento; GV: 18 por cento) quanto durante 15 dias (S: 52 por cento; GB: 51 por cento; GV: 11 por cento), mas não foi suficiente para minimizar a redução do peso muscular. CONCLUSÕES: O tratamento com baixa dose de estrógeno minimizou as alterações metabólicas musculares desencadeadas pela desnervação, porém não foi eficaz em interferir na perda de peso do músculo sóleo, sugerindo que o hormônio atua permitindo uma proteção quimiometabólica com similaridades de ação da via insulínica, porém esse efeito é multifatorial, dependendo da dose, da forma, do tempo de tratamento, além do tempo de desnervação.

OBJECTIVE: To evaluate the effects of estrogen on muscles in female rats subjected to hindlimb denervation. METHODS: Female Wistar rats were divided into five groups (n=6): control; denervated 7 days; denervated 15 days; denervated treated with estrogen (200æg/rat, subcutaneously, daily) for 7 days; and denervated treated with estrogen for 15 days. After the experimental periods, glycogen (GLY) evaluations were performed on the soleus (S), white gastrocnemius (WG) and red gastrocnemius (RG), and the soleus was weighed. The statistical analysis was performed using the normality test, ANOVA and Tukey test (p<0.05). RESULTS: The denervation caused a reduction (p<0.05) in GLY over a 7-day period (S: 44 percent, WG: 32 percent; RG: 32 percent) and 15-day period (S: 62 percent, WG: 44 percent; RG: 53 percent), and also S weight reduction (7 days: 29.7 percent; 15 days: 36.6 percent). However, the estrogen treatment caused elevation (p<0.05) of GLY under this condition, both over 7 days (S: 19 percent; WG: 60 percent; RG: 18 percent) and over 15 days (S: 52 percent; WG: 51 percent; RG: 11 percent), but it was not enough to minimize the muscle weight reduction. CONCLUSIONS: The treatment with low doses of estrogen minimized the metabolic alterations induced by denervation, but it was not effective in interfering in the weight loss of the soleus muscle. This suggests that the hormone acts by enabling chemical-metabolic protection that acts like the insulin route, but the effect is multifactorial and depends on the dose, manner and duration of the treatment, as well as the time since denervation.

Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles.

Sea ice and dust flux increased greatly in the Southern Ocean during the last glacial period. Palaeorecords provide contradictory evidence about marine productivity in this region, but beyond one glacial cycle, data were sparse. Here we present continuous chemical proxy data spanning the last eight glacial cycles (740,000 years) from the Dome C Antarctic ice core. These data constrain winter sea-ice extent in the Indian Ocean, Southern Ocean biogenic productivity and Patagonian climatic conditions. We found that maximum sea-ice extent is closely tied to Antarctic temperature on multi-millennial timescales, but less so on shorter timescales. Biological dimethylsulphide emissions south of the polar front seem to have changed little with climate, suggesting that sulphur compounds were not active in climate regulation. We observe large glacial-interglacial contrasts in iron deposition, which we infer reflects strongly changing Patagonian conditions. During glacial terminations, changes in Patagonia apparently preceded sea-ice reduction, indicating that multiple mechanisms may be responsible for different phases of CO2 increase during glacial terminations. We observe no changes in internal climatic feedbacks that could have caused the change in amplitude of Antarctic temperature variations observed 440,000 years ago.

Chemical composition and physical features of summer aerosol at Terra Nova Bay and Dome C, Antarctica.

During the 2002-2003 austral summer field season, aerosol samples were collected at a coastal (Terra Nova Bay--Northern Victoria Land) and an inland site (Dome C--East Antarctic Plateau). The sampling was carried out by stacked filter units made up of two filters at different porosity (5.0 and 0.4 microm at Terra Nova Bay and 3.0 and 0.4 microm at Dome C), able to roughly separate a coarse from a fine fraction. At Dome C, a further investigation on aerosol size distribution was performed by an inertial impactor able to collect aerosol particles on 8 size classes (from 10 to 0.4 microm). Atomic Force Microscopy was applied to the filter collecting the finer fraction in both sites in order to assess the real cut-off value of the filter sandwich apparatus and to reconstruct the volume size distribution. At the employed flow conditions, the real cut-off value was revealed to be about one third with respect to the filter nominal porosity in both stations. The size distribution plots showed a bimodal distribution with a mode centered around 0.22 microm in both the sites and a second broader mode which is centered between 0.3 microm and 1.2 microm diameter at Terra Nova Bay and shifted toward higher values (centred around 1.0 microm diameter) at Dome C. Each filter was analysed for the main and trace ionic components allowing evaluation of the contributions of primary and secondary aerosol sources at the two sites as a function of the particle size class. The coastal site is mainly affected by primary and secondary marine inputs: the sea spray contribution (Na+, Mg2+, Cl- and ssSO4(2-)) is dominant (77% w/w) in the coarse fraction whereas the biogenic source (methanesulfonate and nssSO4(2-)) prevails (67.5% w/w) in the fine fraction. In this fraction a significant contribution (15.5% w/w) is provided by ammonium likely to be related to surrounding penguin colonies. Dome C atmosphere is characterised by fine particles arising from secondary sources and long-range transport processes. The main component in the fine and coarse fractions at Dome C is sulfate whose nssSO4(2-) represents the 99.5% and the 92.3%(w/w) in fine and coarse fraction, respectively. The observed agreement between nssSO4(2-) and methanesulfonate temporal profiles in the fine fraction demonstrates that biogenic emissions dominate the inland background aerosol. Results from the sampling by the 8-stage impactor at Dome C are presented here: chloride and nitrate are mainly deposited on the 10-2.1 microm stages while the highest sulfate concentration was found in the submicrometric fraction which turned out to be the most acidic. Such a distribution is able to prevent nitrate and chloride re-emission as gaseous HCl and HNO3 in the 10-2.1 microm stages, arising from the exchange reaction between chloride and nitrate salts and sulfuric acid. Moreover, the concentration peak observed for nitrate in coarser fractions is probably related also to the formation of hygroscopic NH4NO3 particles and nitrate adsorption on sea salt particles.

Comparison of styrene-7,8-oxide adducts formed via reaction with cysteine, N-terminal valine and carboxylic acid residues in human, mouse and rat hemoglobin.

The reactive metabolite of styrene, styrene-7,8-oxide (SO), reacts with a variety of nucleophilic sites in hemoglobin (Hb) to form SO-Hb adducts. Following the in vitro incubation of SO with blood from humans, NMRI mice and Sprague-Dawley rats, the second-order reaction rate constants were determined for the reaction of SO with cysteine (through both the alpha- and beta-carbons of SO), N-terminal valine (through the beta-carbon of SO), and carboxylic acid (presumably through both the alpha- and beta-carbons of SO) residues in Hb. The rate constants for cysteine adducts vary dramatically between species [2.04, 10.7, 133 L (mol Hb)-1 h-1 (alpha binding) for humans, mice and rats, respectively] and [0.078, 2.16, 20.4 L (mol Hb)-1 h-1 (beta binding), respectively]. The considerably higher rate of reaction with cysteine in rat Hb probably reflects the presence of an additional cysteine residue at position beta 125. Although the rate constants for valine adducts (1.82, 0.80, 0.29 L (mol Hb)-1 h-1, respectively) and COOH adducts (3.55, 1.94, 2.37 L (mol Hb)-1 h-1, respectively) are much more consistent, the inter-species differences are statistically significant for the reaction of SO with the N-terminal valine of Hb. Following the i.p. administration of styrene to mice and styrene and SO to rats, the levels of adducts at each of these sites were used in conjunction with the calculated rate constants to predict the integrated blood doses of SO. While the SO doses predicted from cysteine and valine adducts were very similar, that based upon COOH-binding was significantly different, presumably due to the instability of SO-COOH adducts. This research affirms the use of both cysteine and valine adducts, but not carboxylic acid adducts, as biomarkers of exposure to styrene and SO.

Antibody response of Echinococcus granulosus infected mice: protoscolex specific response during infection is associated with decreasing specific IgG1/IgG3 ratio as well as decreasing avidity.

The antibody response was followed during 68 weeks in 17 Balb/c mice intraperitoneally (i.p.) infected with Echinococcus granulosus protoscoleces (PSC) and in three mice i.p. immunized with dead PSC. Titres of antibodies recognizing peptidic and glucidic PSC epitopes, as well as their isotypic and avidity profiles were followed by ELISA. In addition, antigen recognition patterns were analysed by immunoblot. The response against carbohydrate epitopes was dominant in infected and immunized mice but stronger in the first group. Infected mice showed similar profiles of specific IgG and IgM with maximum titres from week 38 to 53. Although IgG1 and IgG3 were the predominant antibody subclasses, the ratio of IgG1/IgG3 antibody titres as well as antibody avidity decreased during the experiment, encompassing a decrease in recognition of peptidic epitopes. Immunized mice did not show significant levels of specific IgM and, after week 15, showed IgG titres lower than the infected mice. IgG1 was the predominant IgG subclass during all the experiment with background levels of IgG3. The mean Ab avidity was high and showed no significant changes during immunization. Different patterns of response were thus produced by dead and developing live parasites. Although high avidity IgG1 antibodies were early found in both cases, lower avidity IgG3 antibodies were increasingly produced afterwards only in infected animals. The isotype switch and avidity decrease observed only during infection are consistent with a possible parasitic mechanism to evade host immunity.

Ring test for the determination of N-terminal valine adducts of styrene 7,8-oxide with haemoglobin by the modified Edman degradation technique.

A ring-test was organised between three laboratories using different versions of the modified Edman degradation technique for the gas chromatographic-mass spectrometric determination of N-terminal valine adducts of styrene 7,8-oxide. The analyses were performed on a sample of human haemoglobin reacted in vitro with styrene 7,8-oxide and on a set of five haemoglobin samples from mice dosed by i.p. injection of styrene. Strong correlations between the haemoglobin adduct determinations of the different laboratories were observed. However, covariance analysis revealed different slopes for the dose-response curves, indicating differences for the calibration of the reference globin or reference peptide.

Adduct formation on DNA and haemoglobin in mice intraperitoneally administered with styrene.

Styrene-specific N-7- and O6-guanine DNA adducts and N-terminal valine adducts were determined in mice tissues after the intraperitoneal administration of styrene. Blood, liver, lungs and spleen were collected 3 h after administration of various doses (from 0 to 4.35 mmol/kg b.w.) of styrene. DNA adducts were analysed by the modified 32P-postlabelling assay and N-terminal valine adducts were detected by GC-MS according to the modified Edman degradation technique. In the dose-range studied, for all adducts a clear dose-response relationship was observed. 7-Alkylguanines and O6-styrene guanine adducts were most abundant in lungs, approximately 30% more than in liver and spleen. In all analysed tissues 7-alkylguanines were more abundant than O6-styrene guanine adducts. We found a considerably lower rate of N-terminal valine adduct formation as compared with both DNA adducts. The ratio between 7-alkylguanines and O6-guanine adducts was 1.9, 1.6 and 7.8 in liver, lung and spleen, respectively. In vitro determination of both DNA adducts by 32P-postlabelling resulted also in a lower ratio than that reported earlier using an HPLC analysis. All correlation's between dose, haemoglobin and DNA adducts were very high and significant. However, at the highest injected doses the adduct formation showed a levelling off. To explain this phenomenon a model simulation was performed revealing that 3 h after the injection of the higher doses styrene was not completely converted into styrene-7,8-oxide.

Urinary mandelic acid and hemoglobin adducts in fiberglass-reinforced plastics workers exposed to styrene.

OBJECTIVES: A field study was undertaken to investigate the effects of occupational styrene exposure on mandelic acid excretion and the formation of styrene-7,8-oxide hemoglobin adducts. Especially the sensitivity of a gas chromatography-mass spectrometry method for determining hemoglobin adducts was evaluated. METHODS: Over a four-week period, each individual of a group of 52 fiberglass-reinforced plastics workers was monitored once a week by the simultaneous measurement of styrene in the air and urinary postshift mandelic acid. In addition mandelic acid and hemoglobin adducts were monitored in a group of 24 unexposed referents. At the end of the monitoring period styrene-7,8-oxide adduct formation on N-terminal valine in hemoglobin was examined by gas chromatography-mass spectrometry according to the modified Edman degradation technique. RESULTS: Personal air samples showed an average styrene exposure of 31 mg.m-3. The average postshift mandelic acid was 98 mg.g creatinine-1. For workers not wearing respirators and not showing breath ethanol, the correlation coefficient between styrene and mandelic acid was 0.78. The blood samples were analyzed for styrene-7,8-oxide adducts on hemoglobin. With a detection limit of 10 pmol.g-1, no styrene-7,8-oxide adducts were found under these exposure conditions. CONCLUSION: Adduct formation in humans is less effective than in mice. In comparison with ethylene, styrene is at least 70 times less effective in forming hemoglobin adducts. Investigating adduct formation in humans at or below the exposure levels reported in this study would require a detection limit of about one order of magnitude better.

Use of specific antibody and circulating antigen serum levels in the hydatid immunodiagnosis of asymptomatic population.

Levels of specific antibodies (Ab) and circulating antigens (CAg) were tested by ELISA in sera from 115 surgically confirmed hydatid patients, 41 individuals exhibiting other parasitic and unrelated diseases and 69 healthy subjects. Addition of CAg data to Ab detection in this sera collection increased sensitivity from 85% (only Ab) to 89% (Ab + CAg). Combination of ultrasonography with Ab and CAg serology for diagnosis of asymptomatic population in endemic areas was analyzed. One field survey (163 persons) involved both blood extraction and ultrasonography to all the population. Three people exhibited cyst images and all of them were Ab positive, while 6 Ab and 1 CAg positive individuals exhibited no cyst image. Another survey (1620 persons) involved a selection of 85 subjects for serology according to ultrasound data and record of family hydatid history. Twelve per cent exhibited no hydatid image being serologically positive and 14% were serologically negative but exhibited cyst image. Ultrasonography and serology (Ab and CAg) should be used in combination to maximize the diagnostic yield in asymptomatic population.