Steroids 51. An improved synthesis of ORG 2058 and the synthesis of [3H]ORG 2058.

16 alpha-Ethyl-21-hydroxy-19-norpregn-4-ene-3,20-dione (ORG 2058) is a ligand widely used in progesterone receptor assays. An improved synthesis of the compound is reported, starting from norethisterone acetate. The preparation of the tritiated radioligand [3H]ORG 2058 is also described.

A computer model of the convulsive membrane.

A computer model of the convulsive membrane was built up by combining the H-H equations of normal ionic currents with a pathological current flowing through calcium channels and carrying sodium ions. Thus any form of paroxysmal depolarization shift could be simulated, by varying two rate constants and potassium conductance. The simulated PDSs are initiated by a minimal conductance pulse and terminate spontaneously according to the inherent rules of the model system.

The appearance of direct contacts between Auerbach's plexus and smooth muscle cells in the small intestine of the chicken during in ovo development.

Direct contacts between the neural cell bodies of Auerbach's ganglia and the longitudinal smooth muscle cells in the chicken small intestine were demonstrated by electron microscopy during the second half of embryonic development. The possible functional explanation of these contacts is discussed.

Optic terminals form axosomatic synapses with deep tectal neurons in Bufo marinus.

Previous studies have shown that a small proportion of the retinal fibres to the optic tectum terminates in the deep tectal cellular layers (layers 6 and 4) in Anura. Horseradish peroxidase was applied to the cut central end of the optic nerve of Bufo marinus to study the synaptic connections of these retinotectal afferents. Some of the retinotectal afferents arrive at the deep tectal layers and form synapses with dendrites (7% of all tectal inputs) and on the somata of the deep tectal cells (0.

Seasonal variations in acetylcholine content and the levels of cholinergic enzymes in the alimentary tract and heart of Rana esculenta L.

The acetylcholine (ACh) content and the relative levels of choline-acetyltransferase (ChAT) and acetylcholinesterase (AChE) were measured in the stomach and intestinal musculature and in the heart muscles of frogs (Rana esculenta L.) during hibernation (January-stage 1), low activity (April-stage 2) and high activity period (July-stage 3). The ACh content doubled in the stomach from stage 1 to 2, then little change occurred.

Stable incorporation of genetic material into the chromosome of Rhizobium meliloti 41: construction of an integrative vector system.

An integrative vector system has been developed from the site-specific recombination elements of temperate phage 16-3. The system can be used for highly efficient stable introduction of genetic material into the chromosome of the symbiotic nitrogen-fixing organism, Rhizobium meliloti 41 (Rm41) at the attB site. Vectors carrying the phage-borne attachment site were constructed, and helper phages providing the site-specific recombination functions in trans were isolated.

Inhibition of tumor induction in tobacco by Agrobacterium tumefaciens and nodulation induced by Rhizobium meliloti in the presence of phenothiazines and structurally related compounds.

Plasmids of Agrobacterium tumefaciens and Rhizobium meliloti carrying Kanamycin resistance genes were eliminated from 1.4 to 0.2% of the growing bacterial cultures by promethazine and imipramine.

A kinetic approach to the thermal inactivation of an immobilized triosephosphate isomerase.

The process of thermal inactivation of triosephosphate isomerase covalently attached to a silica-based support activated with p-benzoquinone was found to be a complex one. At 50 degrees C, a characteristic activation preceding the thermal inactivation was observed. Following the intramolecular changes caused by heat, the values of K(M) and V(max) were determined during the activation.

Transfer of isolated nuclei into protoplasts of Aspergillus nidulans.

Nuclei were isolated from protoplasts of a haploid auxotrophic Aspergillus nidulans strain. Transformation of protoplasts prepared from a complementary haploid auxotrophic strain with these purified nuclei resulted in both heterokaryotic and diploid colonies. The nutritionally-complementing colonies appeared at a frequency of 5 x 10(-7) to 10(-8).

Stimulation of substantia nigra pars reticulata suppresses neocortical seizures.

The effects of unilateral electrical stimulation of the substantia nigra pars reticulata (SNpr) on the electrocorticographic (ECoG) manifestations of seizures were studied in anesthetized rats. Epileptiform activity was provoked in the primary focus (Pf) by unilateral, local application of 3-aminopyridine which induced secondary focus in the homologous area of the contralateral cortex (mirror focus, Mf). The position of the electrode for stimulation of SNpr was contralateral to the Pf.

Some morphological and histochemical features of the midgut myenteric plexus of the common European frog, Rana esculenta.

The neuron morphology and distribution of four putative transmitters were investigated in the myenteric plexus of frog (Rana esculenta) midgut. The gross morphology was revealed by NADH-diaphorase histochemistry, and the shape of the neurons by silver impregnation. Nerve cells had heterogeneous distribution: they either formed ganglia or placed as solitary neurons in the duodenum, while in the rest of the midgut only solitary neurons were observed.

Interaction of pyrophosphate ion with di-, tri- and tetra-amines in aqueous solution: a potentiometric and calorimetric study.

Successive macroscopic pKa values have been determined potentiometrically for the conjugate acids of spermidine (4-azaoctane-1,8-diamine), spermine (4,9-diazadodecane-1,12-diamine) and some acylic diamines at various ionic strengths in the absence and presence of tetrasodium pyrophosphate. The stability of the amine/pyrophosphate adducts have been estimated on the basis of effects of the pyrophosphate ion on the apparent acidity constants of the amines. Stoichiometry and thermodynamics of adduct formation have been elucidated from microcalorimetric measurements.

Novel synthesis of cholesterol analogs: condensation of pregnenolone with dihydropyran or dihydrofuran.

Pregnenolone 3-(2'-tetrahydropyranyl) ether (1) was condensed with 3,4-[2H]dihydropyran to mainly give (20R)-[6'-(3',4'-[2'H]dihydropyranyl)]-pregn-5-ene-3 beta,20-diol 3-(2'-tetrahydropyranyl) ether (20R-3), according to nuclear magnetic resonance (NMR). Cold, dilute HCl in ethanol removed the tetrahydropyranyl group at C-3 and also opened the dihydropyranyl ring at the C-20 position of 20R-3 to give (20R)-27-norcholest-5-en-22-one-3 beta,20,26-triol (20R-5). Analogous results were obtained by condensing pregnenolone 3-acetate with 3,4-[2H]dihydropyran to provide (20R)-[6'-(3',4'-[2'H]dihydropyranyl)]-pregn-5-ene-3 beta,20-diol 3-acetate (20R-4).

Isolation of nuclei from Aspergillus nidulans protoplasts.

Intact nuclei were isolated from the protoplasts of the filamentous fungus Aspergillus nidulans. The large amounts of protoplasts required for such nuclear preparations were produced from young mycelia grown in liquid culture. For final purification of the crude nuclear fraction, a Nycodenz density-gradient centrifugation was applied.

The preparation of 2,4-dibromoestra-1,3,5(10),6-tetraene-3,17 beta-diol diacetate.

[2,4,6,7-3H4]Estradiol is used for the quantitative determination of estradiol receptors. The synthesis of 2,4-dibromoestra-1,3,5(10),6-tetraene-3,17 beta-diol 3,17-diacetate, the convenient precursor of [2,4,6,7-3H4]estradiol, is described. 6-Alkoxy compounds were also prepared and investigated.

The isolated N-terminal DNA binding domain of the c repressor of bacteriophage 16-3 is functional in DNA binding in vivo and in vitro.

The 197 amino acid c repressor of the temperate Rhizobium meliloti phage 16-3 still regulates the OR operator of the phage after removal of its carboxyl terminal region. When cloned in the low-copy-number plasmid pGA46, a severely truncated variant (R1-77), which retains only the first 77 amino acids of the intact protein, repressed in vivo transcription from the phage promoter PR. When the R1-77 repressor was fused to E.

Characterization of interspecific hybrids within the Aspergillus nidulans group by isoenzyme analysis.

A comparison of interspecific hybrids within the Aspergillus nidulans species group was made by isoenzyme analysis. The gel electrophoretic patterns of the parental species were distinct for most of the enzymes tested. The hybrids were distinguishable from their parents by isoenzyme patterns.

Properties of associative long-lasting potentiation induced by cellular conditioning in the motor cortex of conscious cats.

Mechanisms of long-lasting potentiation of synaptic responses induced in the thalamocortical and recurrent collateral pathways of the pyramidal tract were studied in intracellular recordings from the motor cortex of unanesthetized, chronically implanted cats. The observations provide the first description of long-lasting potentiation in the unanesthetized neocortex in vivo. Monosynaptic excitatory postsynaptic potentials of 2-5 mV in amplitude were evoked as test responses by stimulation of the pyramidal tract and thalamic ventrolateral nucleus at 0.

GABA immunocytochemistry reveals five morphologically different nerve cell types in the frog stomach.

GABA (gamma-aminobutyric acid) immunocytochemistry was used on whole mounts of the frog stomach muscular layer to identify the GABAergic elements of the myenteric plexus. Between the labelled nerve fibres, five morphologically different types of neurons were revealed. The same cell types were also observed in the NADH-diaphorase-labelled control preparations.

Distribution of substance p-like immunoreactivity in nerves of the gastrointestinal tract of the frog Rana esculenta L.

Substance P-like immunoreactivity in the alimentary canal of the frog Rana esculenta L. was studied by means of the indirect immunoperoxidase method. In all segments of the gastrointestinal tract, immunoreactivity was revealed in both the myenteric and the submucosa plexus.

Intracellular Mg2+ modulates the A-current and its blockage by catechol in isolated Lymnaea neurons.

The effects of intracellular Mg2+ (2-8 mM) upon the transient outward current (the A-current) under normal conditions and under catechol-induced blockage were studied in molluscan neurons by using the voltage-clamp and intracellular dialysis techniques. Identified giant Lymnaea stagnalis L. neurons were investigated at room temperature (20-22 degrees C).

Endonuclease-free, protoplast-forming enzyme preparation and its application in fungal transformation.

An endonuclease-free, protoplast-forming enzyme complex was prepared from the "snail enzyme." The purified preparation has high protoplast-forming activity comparable to the crude enzyme complex without destroying circular plasmid DNA. Furthermore, a higher transformation rate was achieved by the application of the endonuclease-free enzyme complex in both yeast and filamentous fungal vector-host systems.

The effects of pesticides on some biochemical parameters of carp (Cyprinus carpio L.).

Treatments with copper sulphate (CuSO4), paraquat (PQ) and methidathion (MD) caused tissue damage and stress effects in carp, indicated by the increased lactate dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT), and glutamate dehydrogenase (GIDH) enzyme activities and elevated blood-sugar levels. Copper sulphate, administered together with PQ and MD, were synergistic in terms of tissue damage and stress effects. The isoenzyme patterns showed organ-specific tissue damage.