Circadian oscillations of DNA synthesis in rat brain.

The possibility that the synthesis of brain DNA undergoes a circadian fluctuation was examined in male adult Wistar rats, kept under natural lighting conditions or born and raised under artificial lighting conditions. Groups of rats were taken every 4 h during the 24 h, injected subcutaneously with [methyl-3H]thymidine and killed 4 h later. By cosinor analysis, the DNA specific activity of cerebral hemispheres and brainstem was found to show a significant 24 h rhythm with the peak at the beginning of the dark period (waking period). By contrast, in kidney, the peak of the circadian rhythm of DNA specific activity occurred during the light period (sleep period), in agreement with literature data. On the other hand, in 4-week-old rats, born and raised in artificial lighting conditions, brain DNA specific activity followed a 12 h rhythm, in agreement with the lack of a significant diurnal oscillation of the sleep--waking structure. It is concluded that brain DNA synthesis undergoes a circadian fluctuation in association with the circadian rhythm of waking.

Paradoxical sleep deprivation of the mother enhances DNA synthesis in fetal rat brain: autoradiographic and biochemical evidence.

Pregnant rats were deprived of paradoxical sleep for 3 days starting on the 18th gestational day. The condition of PS-D was imposed by confinement on a small platform surrounded by water or by daily injections of clomipramine. Four hours before the killing rats received a s.c. injection of [3H]-thymidine. The amount of radioactive DNA determined by autoradiography in several regions of fetal brain was found to be markedly increased under both experimental conditions in comparison with the control fetal brain. Considerably more limited effects were observed in kidney. Comparable changes of lower magnitude were obtained by comparing the specific radioactivity of DNA samples purified by chlorophorm extraction and digestion with RNase and proteinase K. The results fully confirm our previous data obtained under similar experimental conditions but based on the analysis of an acid-washed DNA fraction.

Effect of paradoxical sleep deprivation on dna synthesis in fetal rat brain.

We have investigated the effect of PS-D induced in gestating rats by treatment with clomipramine or with the platform technique on the process of DNA synthesis taking place in fetal organs. This parameter was taken as a biochemical index of ongoing cellular proliferation. In brain and, to a minor extent, in liver and kidney the rate of fetal DNA synthesis was markedly increased in both experimental groups. The effect was more prominent in the clomipramine group. PS-D treatment of gestating rats, notably by the platform technique, left long-lasting effects in the offspring with regard to organ weight and DNA concentration as well as to learning capacity. It is concluded that the occurrence of PS in gestating rats may exert a significant influence on fetal development.

Urban air pollution by polycyclic aromatic hydrocarbons: levels and sources of variability.

The atmospheric levels of polycyclic aromatic hydrocarbons (PAHs), measured since the mid-1970s from approximately 60 towns world-wide, are reviewed. For each investigation, a concise description of sampling conditions and analytical methods is also given. The strongly carcinogenic benzo[a]pyrene was typically found in the range of 1-20 ng/m3 in Europe, and around 1 ng/m3 in the USA. For other PAHs, individual concentrations were generally in the range of 1-50 ng/m3 in Europe, 0.1-1 in North and South America and in Australia, 1-10 in Japan, and 10-100 in two towns in India and New Zealand. Data on the size distribution of PAH-containing particles are also presented, showing that PAH content is adsorbed mostly on respirable particles. The ratios of winter to summer levels, and of urban to rural levels, were found in the range of 2-10 in both cases. PAH levels have progressively decreased in the last few decades, most probably due to the introduction of anti-smoke regulations and the decrease of coal burning for heating. Measurements from different investigations can only be compared with great prudence, owing to sampling factors which can affect results. Sources of urban PAH contamination and of the variability in levels are discussed.

[Air pollution from traffic and the risk of tumors]. / Inquinamento atmosferico da traffico e rischio di tumori.

This paper describes the epidemiological evidence on lung cancer and childhood leukemia in relation to traffic-related air pollution, with particular reference to diesel exhausts, polycyclic aromatic hydrocarbons (PAH) and benzene. Recent epidemiological studies strengthen the hypothesis of an increased lung cancer risk related to residential exposure to air pollution and to occupational exposure to diesel exhausts. The evidence on the carcinogenicity of several PAH mixtures comes from occupational studies, while the risk incurred by the general population is difficult to estimate. A few papers suggest that traffic-related air pollution may be associated with an increased risk of childhood leukemia. The observed relative risks are small but the exposure is widespread. Therefore, the overall impact of exposure to current levels of urban air pollution may be substantial.

[Concentrations of PM10 and PM2.5 particulate material in the atmosphere of Rome]. / Misure di materiale particellare PM10 e PM2.5 nell'atmosfera di Roma.

Starting from 1993, various monitoring campaigns were carried out in Rome to determine PM10 and PM2.5. Their results are presented here cumulatively, with the aim of obtaining preliminary information on relationships among these size fractions, in various seasonal periods and in two sites with different characteristics (a road site and an urban background site in a public park). Particles were collected on filter and gravimetrically determined. Both PM10 and PM2.5 concentrations show temporal fluctuations with higher values during winter months. Background concentrations are lower than those contemporaneously measured at the road site only to a limited extent (10-17%). The contribution of PM2.5 to PM10 during the winter semester is higher than during the summer one (67 vs. 52%), with no substantial intersite differences.

[The International Chemical Safety Cards]. / Le Schede internazionali di sicurezza chimica.

Information is given on a new form of safety data sheets for chemical substances: the "International Chemical Safety Cards", that were developed by the "International Programme on Chemical Safety" of the WHO, in cooperation with the Commission of the European Communities. The Cards are prepared by various scientific institutions and then peer-reviewed by a committee of internationally-recognized experts. At the moment, 349 Cards are available in English. The Commission has also translated 78 Cards into the other eight official languages of the European Community. Among the aims of this undertaking, the most significant are: (a) the possibility of comparing risks associated with different substances, through the use of "standard phrases", whose meaning is given in a specific Guide; (b) circulation of information on chemical risks on a global level, particularly in those countries that are not able to make their own evaluations.

[Safety forms for industrial lubricating oils: a working proposal at the national level]. / Le schede di sicurezza per gli oli lubrificanti industriali: una proposta operativa a livello nazionale.

The health and safety data sheets for lubricating oils currently in use present considerable differences regarding the information they provide. Often, the information is either too generalized or incomplete--particularly on the chemical aspects of oils--and therefore the sheets are inadequate for the prevention and control of the occupational risks. For the purposes of harmonization, a data sheet has been prepared which takes into account the specific features of the products, and particularly the handling of confidential data. The most important oil manufacturers have been consulted, and they have agreed to use the data sheet in order to provide information on their products to the local health authorities. The widespread use of this data sheet should enable an easier comparison of the health and safety data of oils to be made, provide a better understanding of the information received and, consequently, evaluate the risks involved.

[Asbestos in brake and clutch factories. Results of an environmental survey]. / L'asbesto nelle fabbriche di freni e frizioni. Risultati di un'indagine ambientale.

Asbestos is an essential ingredient of friction materials: an environmental survey has been carried out in a brake and clutch factory to evaluate the exposure to airborne asbestos fibres. The measurement of the fibre concentrations has been carried out by means of personal and general air sampling on membrane filters, and subsequent counting by phase-contrast microscopy (400 X). In 17 out of 19 operations entailing exposure for a full shift, mean concentrations obtained by means of personal sampling exceeded 1 f/cc, in 11 they exceeded 2 f/cc; the maximum mean concentration value (7,2 f/cc) has been found at the preforming presses. The mean value for all the working operations was 2,8 f/cc. In addition total dust levels were determined: from a comparison between numerical and gravimetric concentrations, it appears that, for the same total dust level, the initial manufacturing stages have a greater asbestos risk; the relations between the results of the two analytical techniques are discussed. The results are compared with those reported in the literature for similar factories.

[Isochroman-4-spiro-4'-piperidine: synthesis and analgesic properties]. / Isocroman-4-spiro-4'-piperidine: sintesi e proprietà analgesiche

The synthesis of some isochroman-4-spiro-4'-piperidines by intramolecular O-methylation of 4-aryl-4-hydroxymethylpiperidines with formaldehyde and their analgesic activity ("hot plate"test in mice) are reported. The introduction of the new ring led to compounds with weak analgesic activity.

Ribosomal RNAs synthesized by isolated squid nerves and ganglia differ from native ribosomal RNAs.

The large rRNA of the squid comprises two chains that may be dissociated by heating at 65 degrees C. A single chain constitutes the small rRNA. Surprisingly, the RNAs synthesized by dissected squid fin nerves and stellate nerves and ganglia differed in size from native rRNAs and did not manifest thermal instability. Nonetheless, they resembled native rRNAs in relative abundance, subcellular distribution, lack of poly(A), and metabolic stability. In addition, newly synthesized RNA was localized in nerve and glial cells, as shown by autoradiographic analysis, and was assembled into 80S ribosomes, which supported the synthesis of neuron-specific neurofilament proteins. Following incubation of nerves and ganglia for >10 h, native rRNAs started to disappear, while two major newly synthesized RNAs progressively accumulated. As a result, after 20 h, native rRNAs were substituted by the two novel RNAs. With use of 32P-cDNA synthesized from the latter RNAs as a probe, the novel RNAs demonstrated a considerable degree of homology with native rRNA in northern analysis. Taken together, the data suggest that in dissected squid nerves and ganglia, the synthesis of native rRNAs is gradually terminated while two novel rRNAs are being synthesized, presumably as a correlate of reactive gliosis and/or neuronal degeneration/regeneration.

Reliability assessment of a gas chromatographic method for polycyclic aromatic hydrocarbons in olive oil.

A quality control test was developed for a gas chromatographic method to determine polycyclic aromatic hydrocarbons in olive oil. Fifteen oil specimens were fortified with eight three- to six-ring polycyclic aromatic hydrocarbons at levels of between 3.0 (approximate detection limit) and 360 micrograms/kg. Three sets of five equally fortified specimens were obtained and assayed at random by three operators. For each fortification level, the means of recovery yield were in the range 56-107%, and were independent of the polycyclic aromatic hydrocarbon congener specificity and the operator's capability. Excluding subsets of data associated with both the fortification level at the detection limit and a deviant polycyclic aromatic hydrocarbon term (benzo[ghi]perylene), an overall mean accuracy of 96% and a precision of 7% were achieved.

Polycyclic aromatic hydrocarbons in olive oils on the Italian market.

The six olive oils and seven virgin olive oils which are most consumed in Italy were analysed for 28 polycyclic aromatic hydrocarbons (PAHs). The aim was to evaluate whether a carcinogenic hazard for the general population can derive from the dietary intake of this food, which is consumed particularly highly in the Mediterranean area. The analytical method involved extraction by liquid-liquid partition, filtration on silica gel, clean-up by thin-layer chromatography on silica gel, and analysis by high-resolution gas chromatography with a flame ionization detector. The 3- and 4-ring PAHs which are most abundant in the environment were found in all samples, at individual levels up to ca. 40 micrograms/kg (for phenanthrene); no important difference was observed between olive oils and virgin olive oils. PAHs which are most suspected of being carcinogenic for humans were not detected (limit of detection, ca. 3 micrograms/kg). The average yearly intake of the detected PAHs through this food was estimated at ca. 0.56 mg per capita.

Circadian rhythms of DNA content in brain and kidney: effects of environmental stimulation.

Male adult Wistar rats kept under natural lighting show circadian rhythms of DNA content and DNA synthesis in the cerebral cortex, cerebellum and kidney. In the cerebral cortex the acrophases of the 2 rhythms almost coincide during the dark period. On the other hand, in kidney, the acrophase of DNA synthesis is phase-advanced by about 14 h with respect to the acrophase of DNA content, which occurs in the dark span, as in the cerebral cortex. Comparable results were obtained in 5 week-old rats raised under artificial lighting conditions (LD 7:19) and exposed for a few days to sensory and social stimulation (an enriched sensory environment). At variance with the latter data, the circadian changes of DNA content and synthesis flattened out and were not statistically significant in the cerebral cortex of 5 week-old rats kept for a few days under conditions of sensory and social deprivation (an impoverished sensory environment). A similar effect occurred in kidney with regard to the rhythm of DNA content, while the circadian rhythm of DNA synthesis remained statistically significant but was phase-delayed by about 6h with respect to the corresponding rhythm occurring in the enriched environment. In sensory impoverished rats, MESOR values of kidney wet weight and DNA specific activity were significantly higher than in sensory enriched rats, while MESOR values of DNA content were significantly lower. The data demonstrate the striking dependence of the circadian variations of DNA content and synthesis on the nature of environmental stimulation.