The relative ethylumbelliferone dealkylase activity characterizing the effect of different inducers on the hydroxylase system in the liver musomes of female mice

d,l-Camphor was detected as a new inducer of hydroxylase in the liver musomes of female mice. After a 2-day inhalation of d,l-camphor, cyt. P-450 and the ethylumbelliferone dealkylase were increased by 250 per cent and the NADPH-cyt. P-450 reductase by 350 per cent. The product [NADPH-cyt. P-450 reductase activity × cyt. P450 concentration] was shown to be a suitable reference parameter for the ethylumbelliferone dealkylase activity in the liver musomes during the treatment with four different inducers. The relative dealkylase activity Q was much decreased during inhalation of cyclohexane or d,l-camphor.

$\text{Q =}\text{mU ethylumbelliferone dealkylase}\text{mU NADPH-cty. P-450 reductase × nmoles cty. P-450/mg protein}$

Obviously these two inducers preferably enhanced cyt. P-450 species with a low dealkylase activity. The Q-values were reproducible. Q was increased by 100 per cent during induction of a MC-sensitive mouse strain with 3-methylcholanthrene, but it was only moderately decreased by induction with phenobarbital. Corresponding to this, methylcholanthrene is known to selectively induce a cyt. P-448 with high dealkylase activity whereas phenobarbital is known to change the hydroxylase specificity in the liver musomes not very much.     

2. Pathologische Anatomie des Mammacarcinoms

ZusammenfaBung Die Morphologie und das Entartungsrisiko präcanceröser Veränderungen der Brustdrüse (intraduktale atypische Epithelproliferation, papillomatöse Proliferationen, Carcinoma lobulare in situ) werden besprochen. Das jeweils geeignetste therapeutische Vorgehen (kurzfristige Kontrolle, s. c. Mastektomie, einfache Mastektomie) wird mitgeteilt. Ein kombiniertes intraoperatives histologisches und cytologisches staging durch Untersuchung der axillären Lymphknoten wurde entwickelt. Ergibt sich dabei ein Stadium I, so wird lediglich die einfache Mastektomie durchgeführt. Im Stadium II wird nach Rotter-Halsted mit präziser Ausräumung auch der Apex und der interpektoralen Lymphknoten operiert.     

Effect of phenobarbital pretreatment on in vitro enzyme kinetics and in vivo biotransformation of benzene in the rat

Phenobarbital pretreatment (50 mg/kg/day for 3 days orally) of male Wistar rats increased V _max of benzene in vitro hepatic microsomal biotransformation about 6-fold without changing K _m . However, benzene blood levels after oral, intraperitoneal, or subcutaneous benzene administration (3–3.5 mmoles/kg) were not influenced by phenobarbital pretreatment. The phenol blood levels after oral or intraperitoneal benzene were increased by phenobarbital pretreatment, but less than expected from in vitro data and only 3 h after benzene administration. Phenol elimination in urine after subcutaneous benzene was not affected by phenobarbital. After oral or intraperitoneal benzene administration, phenol urine excretion closely followed the levels of phenol in blood, i.e., rate of phenol urine excretion was significantly, but shortly increased, and the cumulative urine excretion of phenol increased very little or remained unchanged. Differences between the in vitro and in vivo observations of the effect of phenolbarbital on benzene biotransformation may partly be explained by distribution of benzene, which apparently limited benzene availability for biotransformation (V _d =5.5) and caused rapid decrease of benzene concentrations in blood. Conditions for enzyme activity may have been substantially different in vitro vs. in vivo: in vitro concentrations of benzene were at least by an order of magnitude higher than phenol concentrations, while in vivo, an opposite relation prevailed making a competition for microsomal monooxygenase possible. Cofactor availability may be another rate-limiting step or factor of in vivo benzene biotransformation, as benzene ring hydroxylation requires high energy. The rate of in vitro hepatic microsomal benzene biotransformation proved to be of limited value when predicting benzene quantitative biotransformation in vivo in contradistinction to various substrates where the in vitro and in vivo biotransformation data are in good agreement     

Effect of short-term administration of lead to pregnant rats.

Lead was administred to adult female rats in drinking water (0;0.1:1 and 10 ppm) for 3 weeks before mating, during pregnancy and during 3 weeks after delivery. On day 21 after delivery the mothers and their newborns were sacrified and various parameters of blood -- lead concentration on (Pb-B), hematocrit (Htc), hemoglobin (Hb), free erythrocyte porphyrins (FEP), delta0aminolevulinate dehydratase (ALAD) -- and tissue -- ALAD, free tissue porphyrins (FTP), lead concentration (Pb-T) -- were determined. In mothers a significant increase in Pb-B and Pb concentration in kidney was found in the 10 ppm group, but this increase in lead concentration was not associated with any statistically significant modification of the biochemical parameters. In newborns, lead concentration in blood and in kidney was also significantly increased in the 10 ppm group and this lead exposure was associated with a decrease of the ALAD activity in blood and an increase of FTP in kidney. On the basis of the biochemical parameters investigated one can therefore conclude that the developing organism is more susceptible to the biological action of lead than the organism of adult animals and that the "no-effect" level of lead administered during pregnancy and in the neonatal period is around 1 ppm.     

Die analyse von aluminium im serum und urin zur überwachung emonierter personen

Zusammenfassung Die Einführnung der flammenlosen Atomabsorptionsspektrometrie in die chemische Analytik ermöglicht eine einfache quantitative Bestimmung des Aluminiums im biologischen Material. Die verwendeten Analysen-methoden und deren Zuverlässigkeitskriterien wurden beschrieben. Entsprechend der heute üblichen Verfahren zur Überwachung schwermetallexponierter Personen wurden von uns bei verschiedenen Kollektiven Aluminiumbestimmungen im Blut und Urin durchgeführt. Untersucht wurde ein Kollektiv von 110 Arbeitern eines Korund-herstellenden und -verarbeitenden Werkes. 82 dieser Arbeiter waren durch staubförmigen Korund exponiert, während 28 Personen an den Öfen zusätzlich noch Metalldämpfen ausgesetzt waxen. Die Expositionsdauer betrug im Mittel 6,9 Jahre. Als Vergleichskollektiv dienten 40 männliche nicht aluminiumexponierte Probanden. Zusädtzlich wurden 33 Dialyse-Patienten, die mit Aluminiumhydroxid (Aludrox) therapiert wurden, in die Studie einbezogen.Für die Aluminiumausscheidung im Urin errechnete sich bei den Normalpersonen eine obere Normgrenze von 30 g/l. Die Ausscheidungswerte der aluminiumexponierten Personen lagen mit einem Median von 39 g Al/l signifikant höher als das Normalkollektiv. Erwartungsgemä zeigten die dampfförmig belasteten Personen einen statistisch signifikant höheren Al-Spiegel im Urin als die staubförmig belastete Gruppe.Die Serumanalysen ergaben keine Hinweise für einen signifikanten Unterschied gegenüber Normalpersonen. Aus den Untersuchungen der Seren von nicht aluminiumexponierten Probanden errechnete sich ein oberer Grenzwert von 35 g/l. Der Serum-Aluminium-Spiegel der exponierten Personen war von der Art und Dauer der Exposition nicht beeinflut. Dagegen lagen die Aluminium-Spiegel im Serum der Dialyse-Patienten im Bereich von 6 – 254 g/l. Bei dieser Patientengruppe mit erhöhten Serum-Aluminiumwerten wurden keine klinischen Zeichen einer manifesten Toxicität gefunden. Damit kommt den Aluminiumkonzentrationen im biologischen Material der aluminiumexponierten Arbeiter keine gesundheitsgefahrdende Relevanz zu.Bei der inhalativen Aufnahme von Aluminium scheint die Menge des resorbierten und in die Blutbahn übergehenden Aluminiums gering zu sein. Hinweise für eine Akkumulation des Metalls im Organismus wurde bei Versuchen mit D-Penicillamin nicht gefunden.Aluminiumbestimmungen im Serum oder Harn sind für die Überwachung von Korund-herstellenden und -verarbeitenden Personen nach diesen Ergebnissen nicht notwendig. Bei Substanzen, wie dem Aluminium, mit geringer Resorptions-quote und groer Toleranzbreite für den menschlichen Organismus sowie ohne manifeste signifikante Gesundheitsschäden erscheint ein Biological Monitoring nicht indiziert.D 29     

Scorpion alpha and alpha-like toxins differentially interact with sodium channels in mammalian CNS and periphery

Scorpion alpha-toxins from Leiurus quinquestriatus hebraeus, LqhII and LqhIII, are similarly toxic to mice when administered by a subcutaneous route, but in mouse brain LqhII is 25-fold more toxic. Examination of the two toxins effects in central nervous system (CNS), peripheral preparations and expressed sodium channels revealed the basis for their differential toxicity. In rat brain synaptosomes, LqhII binds with high affinity, whereas LqhIII competes only at high concentration for LqhII-binding sites in a voltage-dependent manner. LqhII strongly inhibits sodium current inactivation of brain rBII subtype expressed in HEK293 cells, whereas LqhIII is weakly active at 2 microM, suggesting that LqhIII affects sodium channel subtypes other than rBII in the brain. In the periphery, both toxins inhibit tetrodotoxin-sensitive sodium current inactivation in dorsal root ganglion neurons, and are strongly active directly on the muscle and on expressed muI channels. Only LqhII, however, induced repetitive end-plate potentials in mouse phrenic nerve-hemidiaphragm muscle preparation by direct effect on the motor nerve. Thus, rBII and sodium channel subtypes expressed in peripheral nervous system (PNS) serve as the main targets for LqhII but are mostly not sensitive to LqhIII. Toxicity of both toxins in periphery may be attributed to the direct effect on muscle. Our data elucidate, for the first time, how different toxins affect mammalian central and peripheral excitable cells, and reveal unexpected subtype specificity of toxins that interact with receptor site 3.     

Specific activation of the mu opioid receptor (MOR) by endomorphin 1 and endomorphin 2

The recently discovered endomorphin 1 (Tyr-Pro-Trp-Phe-NH2) and endomorphin 2 (Tyr-Pro-Phe-Phe-NH2) were investigated with respect to their direct receptor-binding properties, and to their ability to activate G proteins and to inhibit adenylyl cyclase in both cellular and animal models. Both tetrapeptides activated G proteins and inhibited adenylyl cyclase activity in membrane preparations from cells stably expressing the mu opioid receptor, an effect reversed by the mu receptor antagonist CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2), but they had no influence on cells stably expressing the delta opioid receptor. To further establish the selectivity of these peptides for the mu opioid receptor, brain preparations of mice lacking the mu opioid receptor gene were used to study their binding and signalling properties. Endomorphin 2, tritiated by a dehalotritiation method resulting in a specific radioactivity of 1.98 TBq/mmol (53.4 Ci/mmol), labelled the brain membranes of wild-type mice with a Kd value of 1.77 nM and a Bmax of 63.33 fmol/mg protein. In membranes of mice lacking the mu receptor gene, no binding was observed, and both endomorphins failed to stimulate [35S]guanosine-5'-O-(3-thio)triphosphate ([35S]GTPgammaS) binding and to inhibit adenylyl cyclase. These data show that endomorphins are capable of activating G proteins and inhibiting adenylyl cyclase activity, and all these effects are mediated by the mu opioid receptors.     

Mapping of c-fos gene expression in the brain during morphine dependence and precipitated withdrawal, and phenotypic identification of the striatal neurons involved

The c-fos gene is expressed in the central nervous system in response to various neuronal stimuli. Using in situ hybridization, we examined the effects of chronic morphine treatment and withdrawal on c-fos mRNA in the rat brain, and particularly within identified striatal neurons. Morphine dependence was induced by subcutaneous implantation of two pellets of morphine for 6 days and withdrawal was precipitated by administration of naltrexone. Placebo animals and morphine-dependent rats showed a very weak c-fos mRNA expression in all the structures studied. Our study emphasized the spatial variations in c-fos mRNA expression, and also revealed a peak expression of c-fos mRNA at 1 h after naltrexone-precipitated withdrawal in the projection areas of dopaminergic neurons, noradrenergic neurons and in several regions expressing opiate receptors. Interestingly, morphine withdrawal induces c-fos mRNA expression in the two efferent populations of the striatum (i.e. striatonigral and striatopallidal neurons) both in the caudate putamen and nucleus accumbens. Moreover, the proportions of activated neurons during morphine withdrawal are different in the caudate putamen (mostly in striatopallidal neurons) and in the shell and core parts of the nucleus accumbens (mostly in striatonigral neurons). The activation of striatopallidal neurons suggests a predominant dopaminergic regulation on c-fos gene expression in the striatum during withdrawal. On the contrary, c-fos induction in striatonigral neurons during withdrawal seems to involve a more complex regulation like opioid-dopamine interactions via the mu opioid receptor and the D1 dopamine receptor coexpressed on this neuronal population or the implication of other neurotransmitter systems.     

Norepinephrine regulation of growth hormone release from goldfish pituitary cells. II. Intracellular sites of action

Previous results suggest that norepinephrine decreases growth hormone (GH) release in goldfish by means of alpha-2 adrenoceptor activation. The intracellular mechanisms by which norepinephrine inhibits GH release were examined in the present study using dispersed goldfish pituitary cells. In 2-h static incubation experiments, norepinephrine and the alpha-2 agonist clonidine decreased basal GH release and the GH responses to stimulation by the dopamine D1 agonist SKF38393 and two native gonadotropin-releasing hormones (GnRH). Norepinephrine also reduced GH responses to the adenylate cyclase activator forskolin, two protein kinase C (PKC) activators (phorbol ester and synthetic diacylglycerol), and two Ca2+ ionophores (ionomycin and A23187). Similarly, norepinephrine applied as a 1-h pulse in cell column perifusion experiments reduced basal GH release and abolished the GH response to a 5-min pulse of arachidonic acid. In goldfish, D1-stimulated GH release is mediated by AC-, arachidonic acid-and Ca2+-dependent pathways, whereas GnRH action is coupled to PKC-and Ca2+-dependent mechanisms. These results suggest that norepinephrine activation of alpha-2 receptors inhibits ligand-induced GH secretion by actions subsequent to activation of these second messenger cascades. To further characterize norepinephrine mechanisms of action on unstimulated hormone release, the ability of norepinephrine and an alpha-2 agonist to affect activation of two second messenger cascades under basal conditions was also investigated. Static incubation with clonidine reduced cAMP production in a time-and dose-dependent manner, suggesting that norepinephrine inhibitory action can also be expressed at the level of cAMP production. Resting intracellular free calcium levels in single, identified goldfish somatotropes was unaffected by norepinephrine. However, the inhibitory effects of norepinephrine on basal GH secretion was not observed in the presence of a voltage-sensitive Ca2+ channel agonist. Whether these channels are targets for norepinephrine action on unstimulated GH release requires further investigation.