'Normal' cigarette smoking increases free cortisol in habitual smokers.

In habitual smokers salivary cortisol responses to cigarette smoking were investigated. In the first study, 31 adults assigned to two experimental groups smoked either one or two cigarettes of their preferred brand. Mean salivary cortisol levels were significantly elevated after smoking of two cigarettes. In the second study, 10 smokers and 10 nonsmokers provided saliva samples at 20 min intervals over a 12-hr period. While environmental stimuli were paralleled in both groups overall cortisol output was significantly elevated in the smokers. These data suggest that 'normal' cigarette smoking can increase free cortisol levels.     

Cytogenotoxicity biomarkers in fat snook Centropomus parallelus from Cananéia and São Vicente estuaries, SP, Brazil

The aquatic environment receives many contaminants that can induce damages at the molecular, biochemical, cellular and physiological levels. Centropomus parallelus, an important food resource for local populations, is a predator fish that feeds on small fishes and benthic invertebrates, thus being vulnerable to the bioconcentration and biomagnification processes. This study aimed to evaluate cytogenotoxic responses in erythrocytes from C. parallelus juveniles collected in the Cananéia and São Vicente estuaries, both in winter and in summer. After anesthesia, blood samples were collected by caudal puncture. Blood smears were prepared on glass slides and stained with May-Grünwald-Giemsa dye. Two thousand cells were analyzed per slide (1000x), and nuclear abnormalities (NA) and micronuclei (MN) were scored. The São Vicente sample showed MN and NA frequencies (%/1000 cells) of 0.325 and 3.575, in winter, and of 0.125 and 2.935 in summer respectively; the Cananéia sample showed frequencies of 0.0325 and 0.03, in winter, and of 0.065 and 0.355 in summer, respectively. The rates found in São Vicente were significantly higher than those found in Cananéia, evidencing that the levels of pollution in that estuary were high enough to induce genetic damages.     

Temperature response of parameters of a biochemically based model of photosynthesis. II. A review of experimental data

The temperature dependence of C₃ photosynthesis is known to vary with growth environment and with species. In an attempt to quantify this variability, a commonly used biochemically based photosynthesis model was parameterized from 19 gas exchange studies on tree and crop species. The parameter values obtained described the shape and amplitude of the temperature responses of the maximum rate of Rubisco activity (V_cmax) and the potential rate of electron transport (J_max). Original data sets were used for this review, as it is shown that derived values of V_cmax and its temperature response depend strongly on assumptions made in derivation. Values of J_max and V_cmax at 25 °C varied considerably among species but were strongly correlated, with an average J_max : V_cmax ratio of 1·67. Two species grown in cold climates, however, had lower ratios. In all studies, the J_max : V_cmax ratio declined strongly with measurement temperature. The relative temperature responses of J_max and V_cmax were relatively constant among tree species. Activation energies averaged 50 kJ mol^?1 for J_max and 65 kJ mol^?1 for V_cmax, and for most species temperature optima averaged 33 °C for J_max and 40 °C for V_cmax. However, the cold climate tree species had low temperature optima for both J_max(19 °C) and V_cmax (29 °C), suggesting acclimation of both processes to growth temperature. Crop species had somewhat different temperature responses, with higher activation energies for both J_max and V_cmax, implying narrower peaks in the temperature response for these species. The results thus suggest that both growth environment and plant type can influence the photosynthetic response to temperature. Based on these results, several suggestions are made to improve modelling of temperature responses.     

Ontogeny and evolution of electric organs in gymnotiform fish

In order to further our understanding of the evolution of electric organs in the Neotropical gymnotiform fish, we studied the ontogeny of the electric organs in eight species. In Eigenmannia virescens, Sternopygus macrurus, and Apteronotus leptorhynchus the earliest electrocytes are located between muscle fibres of the hypaxial muscle (Type A electrocytes). We present arguments that these Type A electrocytes represent the plesiomorphic condition. In S. macrurus, in addition to the electrocytes in the hypaxial muscle, additional electrocytes were found in the epaxial muscle. In A. leptorhynchus a neurogenic organ develops later during ontogeny in the medial part of the hypaxial muscle in addition to the early myogenic organ. In E. virescens the early electrocytes in hypaxial muscle will degenerate later during ontogeny, and this organ will be replaced functionally by electrocytes located in the caudal appendage and below the hypaxial muscle. In Electrophorus electricus, two Gymnotus species, Rhamphichthys sp., and Brachyhypopomus pinnicaudatus the first electrocytes were found below the hypaxial muscle (Type B electrocytes); they are assumed to be the more derived stage. In R. sp., and B. pinnicaudatus the electrocytes of Type B developed directly into the adult organ. In the two Gymnotus ssp. electrocytes were also found in the medial part of the organ in-between muscle fibres of the hypaxial muscle. In E. electricus a germinative zone was observed to separate from the ventral myotome. This zone is generating electrocytes continuously so that, as a consequence, the relative proportion of electric organ to muscle increases greatly. In 45 mm long E. electricus a separation of low voltage orientation pulses and high voltage trains of pulses (shocks) was observed. A first appearance of Hunter’s organ was found in 140 mm specimens of E. electricus. The first discharges of all species studied were head- positive, with the exception of R. sp., which produced a triphasic discharge, its main component, however, being head-positive. The arguments presented indicate that the Type A electrocytes found in E. virescens, S. macrurus, and A. leptorhynchus would represent the plesiomorphic condition. On the basis of the evidence regarding the formation, cytological appearance, and anatomical location, as well as the early electrical recordings, we would hypothesise that during the evolution of gymnotiforms wave type species evolved first, and in a second step pulse type species followed. This view, however, is corroborated by only some phylogenetic hypotheses.     

The role of shear stress in atherosclerosis

Atherosclerotic lesions preferentially localize near side branches or curved vessels. During the last few decades, research has been shown that low or low and oscillating shear stress is associated with plaque location. Despite ample evidence, the precise mechanism is unknown. This is mainly because of a lack of appropriate animal models. We describe two novel methods to study the hypothesis that shear stress acts through endothelial gene expression or shear stress acts through localizing of inflammation. Both literature evidence and own findings support a role for both mechanisms in atherosclerosis.     

Monitoring the initial pulmonary absorption of two different beclomethasone dipropionate aerosols employing a human lung reperfusion model

Background

The pulmonary residence time of inhaled glucocorticoids as well as their rate and extend of absorption into systemic circulation are important facets of their efficacy-safety profile. We evaluated a novel approach to elucidate the pulmonary absorption of an inhaled glucocorticoid. Our objective was to monitor and compare the combined process of drug particle dissolution, pro-drug activation and time course of initial distribution from human lung tissue into plasma for two different glucocorticoid formulations.

Methods

We chose beclomethasone dipropionate (BDP) delivered by two different commercially available HFA-propelled metered dose inhalers (Sanasthmax^®/Becloforte™ and Ventolair^®/Qvar™). Initially we developed a simple dialysis model to assess the transfer of BDP and its active metabolite from human lung homogenate into human plasma. In a novel experimental setting we then administered the aerosols into the bronchus of an extracorporally ventilated and reperfused human lung lobe and monitored the concentrations of BDP and its metabolites in the reperfusion fluid.

Results

Unexpectedly, we observed differences between the two aerosol formulations Sanasthmax^®/Becloforte™ and Ventolair^®/Qvar™ in both the dialysis as well as in the human reperfusion model. The HFA-BDP formulated as Ventolair^®/Qvar™ displayed a more rapid release from lung tissue compared to Sanasthmax^®/Becloforte™. We succeeded to explain and illustrate the observed differences between the two aerosols with their unique particle topology and divergent dissolution behaviour in human bronchial fluid.

Conclusion

We conclude that though the ultrafine particles of Ventolair^®/Qvar™ are beneficial for high lung deposition, they also yield a less desired more rapid systemic drug delivery. While the differences between Sanasthmax^®/Becloforte™ and Ventolair^®/Qvar™ were obvious in both the dialysis and lung perfusion experiments, the latter allowed to record time courses of pro-drug activation and distribution that were more consistent with results of comparable clinical trials. Thus, the extracorporally reperfused and ventilated human lung is a highly valuable physiological model to explore the lung pharmacokinetics of inhaled drugs.     

Einfluß von Röntgenstrahlen auf den RNS-Stoffwechsel in Ehrlich-Ascites-Tumorzellen

Zusammenfassung Der Nukleinsäurestoffwechsel von Ehrlich-Ascites-Tumorzellen wurdein vitro nach Bestrahlung untersucht. Dabei zeigte sich — wie auch bei Untersuchungen anderer Autoren — daß die Gesamt-RNS-Synthese durch Röntgenstrahlen kaum beeinflußt wird. In weiteren Experimenten wurde die Kern-RNS nach der Methode von Georgiev u. Mantieva extrahiert, wobei zwei Fraktionen unterschiedlicher Basenzusammensetzung gewonnen werden konnten. Vorherige Bestrahlung der Zellen bewirkte in einem Dosisbereich von 1000 bis 1500 R eine Hemmung des H³-Uridin-Einbaues in die 65°C-Fraktion, während die 50°C-Fraktion vergleichsweise nur geringe Veränderungen aufwies. Untersuchungen zur Beeinflussung bereits synthetisierter RNS durch die Bestrahlung (Chase-Experimente) ergaben keinen beschleunigten Abbau bei den von uns benutzten Dosen und Methoden.

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Summary The metabolism of RNA in irradiated Ehrlich ascites tumor cells was studiedin vitro. It was found — as have earlier investigators too — that the total RNA synthesis in mammalian cells is hardly affected by irradiation. In further experiments cell nuclei were prepared and two RNA fractions with different base composition were isolated according to the method of Georgiev and Mantieva (thermic fractionation). Thereby it was observed that the H³-uridine incorporation into the 65°C fraction decreased at the dose range of 1000 to 1500 R, whereas the 50°C fraction showed no marked changes in RNA synthesis. Experiments on the effect of irradiation on newly synthesized RNA (chase-experiments) produced no observable degradation of RNA under our experimental conditions.

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Herrn Prof. Dr. J. Kühnau zum 70. Geburtstag gewidmet.

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Diese Arbeit wurde mit Unterstiitzung der Deutsehen Forsehungsgemeinsehaft durehgeffihrt.Frau I. Schwenke danken wir ffir gewissenhafte technische Assistenz.