Interaction of medroxyprogesterone acetate with cytosol androgen receptors in the rat hypothalamus and pituitary

The binding of medroxyprogesterone acetate (MPA) with cytosol androgen receptors from rat pituitary and hypothalamus was studied. The pituitary and hypothalamic cytosol androgen receptors from adult castrated female rats were in vitro labeled using 3H natural (testosterone (T) and 5 alpha-dihydrotestosterone (DHT] and [3H]synthetic (methyltrienolone) androgens as radioligands. The [3H]androgen-receptor complexes sedimented with a coefficient of 8S in linear sucrose gradients. When incubated with an excess of radioinert MPA, specific binding was abolished indicating interaction of MPA with androgen receptors. Furthermore specific [3H]MPA-androgen cytosol receptor complexes could be identified in these neuroendocrine tissues when a post-gradient receptor labeling technique was used in the absence or presence of radioinert MPA, DHT, and triamcinolone acetonide. A study of binding kinetics disclosed that the equilibrium dissociation constant and saturation binding capacity for the MPA binder, were similar to those exhibited by DHT binding to androgen receptors in both studied tissues under identical experimental conditions. The overall results were interpreted as demonstrating that MPA interacts with cytosol steroid receptors other than those of progesterone in the rat hypothalamus and anterior pituitary. The data are consistent with MPA binding to androgen receptors.     

Does naloxone have functional significant activity on medial thalamic neurons? microiontophoretical study

Local administration (microiontophoretically) of naloxone was tested in 57 parafascicularis thalamic (PF) neurons of morphine-naive and morphine-dependent rats. In morphine-naive rats microiontophoretic applications of naloxone induced changes in 52% of the PF neurons. Reduction in neuronal activity was observed in the majority of them; this reduction phenomena exhibited dose response characteristics, i.e., each incremental naloxone dose caused further decrease of the neuronal discharges. In morphine-dependent animals, 64% of the PF neurons were affected. The changes seen after naloxone were mainly increases of electrical discharges (i.e. the opposite effects obtained in morphine-naive animals).     

Biochemical parameters to assess cell differentiation of Bouvardia ternifolia Schlecht callus

Calli derived from leaves and radicles of B. ternifolia were grown on Murashige and Skoog (MS) basal medium, and the effects of different nitrogen sources on the rate of callus growth and on the enzymes related to nitrogen assimilation were studied. Ammonium alone did not support callus growth unless a Krebs-cycle intermediate was added to the medium. The activities of glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 1.4.7.1), and glutamate dehydrogenase (EC 1.4.1.2) were measured in homogenates of callus grown on media supplied with different nitrogen sources. The results indicate that leaf and root calli have similar levels of these enzymes when grown on MS medium (Murashige and Skoog 1962. Physiol. Plant. 15, 473–497). However, when the calli were supplied with glutamine as the sole nitrogen source, the activity of glutamate synthase increased in leaf callus but was almost completely inhibited in root callus. The results indicate that calli originated from different B. ternifolia tissues do not have the same biochemical dedifferentiated state.     

Neurophysiology of the motoneurons of the external oculomotor nucleus in the waking cat

The spontaneous and visually induced activity of abducens motoneurons has been recorded in the alert cat. Motoneurons were identified by their antidromic activation from the ipsilateral abducens nerve. All identified motoneurons appeared related to both the position and velocity of the eye in the horizontal plane, although distributed in a wide range. Neural time constants were also measured, showing a mean value similar to that of the mechanical time constant of the oculomotor plant. According to present results, abducens motoneurons of cats and monkeys are very similar, notwithstanding some differences in their activities during saccadic movements.     

Long-acting contraceptive agents: norethisterone esters of monoalkenyl and monoalkynyl acids

The synthesis of nine new esters of norethisterone (17 alpha-ethynyl-17 beta-hydroxyestr-4-en-3-one) is described, with the esterifying acids bearing an acetylenic or olefinic function in a chain of eight or nine carbon atoms, for evaluation as long-acting contraceptive agents.     

Twopictonia (perisphinctidae) from the subbetic upper jurassic of spain

Two ammonites belonging to the genusPictonia Bayle, 1878 (subgenusPachypictonia Schneid, 1940) are described from the Lower Kimmeridgian of the Subbetic of Western Andalusia, this being the first evidence of the presence of this genus in the Mediterranean (Tethydian) Upper Jurassic.     

Desangeloylshairidin,X-ray structure determination of a sesquiterpene lactone from Guillonea scabra

The structure and absolute configuration of desangeloylshairidin, a guaianolide isolated from Guillonea scabra, have been established by X-ray diffraction analysis. No conformational change was observed in its seven-membered ring between the crystal and deuterochloroform solution states.     

A heteroplasmic state induced by protoplast fusion is a necessary condition for detecting rearrangements in Nicotiana mitochondrial DNA

Theoretical and Applied Genetics - Mitochondrial DNA (mtDNA) restriction patterns were studied in mutant, cybrid and somatic hybrid plants regenerated from Nicotiana protoplasts. It has been shown...