Two novel Streptomyces protein protease inhibitors. Purification, activity, cloning, and expression

In contrast to the Gram-negative bacteria, Gram-positive bacteria such as Streptomyces lack a mucopolysaccharide cell wall which allows them to produce and secrete a variety of proteins directly into their environment. In an effort to understand and eventually exploit the synthesis and secretion of proteins by Streptomyces, we identified and characterized two naturally occurring abundantly produced proteins in culture supernatants of Streptomyces lividans and Streptomyces longisporus. We purified these 10-kDa proteins and obtained partial amino acid sequence information which was then used to design oligonucleotide probes in order to clone their genes. Analysis of the sequence data indicated that these proteins were related to each other and to several other previously characterized Streptomyces protein protease inhibitors. We demonstrate that both proteins are protein protease inhibitors with specificity for trypsin-like enzymes. The presumptive signal peptidase cleavage sites and subsequent aminopeptidase products of each protein are characterized. Finally, we show that the cloned genes contain all of the information necessary to direct synthesis and secretion of the proteins by Streptomyces spp. or Escherichia coli.

Buspirone and related compounds as alternative anxiolytics

The desire of the pharmaceutical industry to obtain more selective agents for the treatment of anxiety with fewer or diminished side effects and a profile consistent with safety during long-term use resulted in a search which has identified the azapirones as a new class of anxiolytics which lack structural or biochemical homology with the benzodiazepines. This presentation reviews the efficacy of buspirone (BuSpar), the first of this class to reach wide acceptance, and its analogs, gepirone, ipsapirone, and tandospirone, in the clinical treatment of anxiety and compares their 'anxioselective' profiles to those of the benzodiazepines. The azapirones appear to act as serotonin 5-HT1A partial agonists as they all share high affinity for 5-HT1A binding sites in vitro as well as in anatomical studies. Moreover, their biochemical, electro-physiological, and behavioural actions are consistent with this suggestion. That the serotonergic actions of the azapirones are relevant to their anxiolytic efficacy is suggested by their efficacy in animal models sensitive to other effective anxiolytics as well as their loss of efficacy in such testing following lesions of serotonergic neurons. Thus action upon serotonergic neurotransmission may produce a highly desirable anxioselective profile of effects.

Unique modulation of central 5-HT2 receptor binding sites and 5-HT2 receptor-mediated behavior by continuous gepirone treatment

The effect of continuous treatment with the selective 5-HT1A agonist gepirone upon 5-HT2-mediated behavior and cortical 5-HT2 receptor binding sites was examined in naive rats or rats receiving noradrenergic (DSP4) or serotonergic (5,7-DHT) lesions. Continuous administration of gepirone in non-lesioned rats for 3, 7, or 14 days enhanced the head shake response to the 5-HT agonist quipazine. This enhancement of 5-HT2-mediated behavior occurred despite concomitant down-regulation of cortical 5-HT2 binding sites. However, 28 days of gepirone administration significantly reduced behavioral responsiveness to quipazine. The gepirone-induced facilitation of 5-HT2-mediated behavior observed after 7 days of continuous treatment was blocked in both DSP4 and 5,7-DHT-lesioned rats. However, both noradrenergic and serotonergic denervation failed to modify the down-regulation of 5-HT2 receptor binding sites produced by continuous gepirone administration. These results suggest that the curious dissociation of behavioral and biochemical indices of 5-HT2 receptor function produced by continuous gepirone treatment may be the result of a dual yet separate action of the drug on central presynaptic noradrenergic and serotonergic mechanisms and postsynaptic 5-HT receptors. Furthermore, the postsynaptic action of gepirone which reduces the maximal number of cortical 5-HT2 receptor binding sites may be the result of gepirone's agonist action at postsynaptic 5-HT1A receptors.

Serotonin agents in anxiety

The side effects and unwanted or unnecessary ancillary pharmacological properties of benzodiazepine anxiolytic drugs resulted in a continuing search for new agents with improved profiles of activity. Buspirone was the first novel drug to emerge from this search in almost thirty years. Investigations into its mechanism of action revealed a key role for serotonin in the pharmacotherapy of anxiety. A variety of serotonergic agents are now in preclinical and clinical development as anxiolytics, including 5-HT1A partial agonists, 5-HT2 antagonists, and 5-HT3 antagonists. In addition to the new drugs which will be developed as a consequence of these investigations, their clinical efficacy will prompt the development of new animal models of psychopathology, leading us ever closer to a full understanding of the neurobiological substrates of anxiety. In addition, deployment of these new agents in the armamentaria of the clinician and the basic scientist will lead to new insights into the treatment of other disorders and the biochemical mechanisms by which the effects of these drugs are obtained.

Cloning and expression of cDNA for a human low-Km, rolipram-sensitive cyclic AMP phosphodiesterase

We have isolated cDNA clones representing cyclic AMP (cAMP)-specific phosphodiesterases (PDEases) from a human monocyte cDNA library. One cDNA clone (hPDE-1) defines a large open reading frame of ca. 2.1 kilobases, predicting a 686-amino-acid, ca. 77-kilodalton protein which contains significant homology to both rat brain and Drosophila cAMP PDEases, especially within an internal conserved domain of ca. 270 residues. Amino acid sequence divergence exists at the NH2 terminus and also within a 40- to 100-residue domain near the COOH-terminal end. hPDE-1 hybridizes to a major 4.8-kilobase mRNA transcript from both human monocytes and placenta. The coding region of hPDE-1 was engineered for expression in COS-1 cells, resulting in the overproduction of cAMP PDEase activity. The hPDE-1 recombinant gene product was identified as a low-Km cAMP phosphodiesterase on the basis of several biochemical properties including selective inhibition by the antidepressant drug rolipram. Known inhibitors of other PDEases (cGMP-specific PDEase, cGMP-inhibited PDEase) had little or no effect on the hPDE-1 recombinant gene product. Human genomic Southern blot analysis suggests that this enzyme is likely to be encoded by a single gene. The presence of the enzyme in monocytes may be important for cell function in inflammation. Rolipram sensitivity, coupled with homology to the Drosophila cAMP PDEase, which is required for learning and memory in flies, suggests an additional function for this enzyme in neurobiochemistry.

H1 antihistamines interact with central sigma receptors

Several antihistamines were evaluated for their ability to interact with sigma, muscarinic and histaminic H1 binding sites in rat brain preparations. All of the antihistamines were able to interact with the sigma site, as well as the other two sites. In addition, tripelennamine was found to elicit sigma-like behaviors when administered to rats. This affinity for the sigma site suggests that the compounds may elicit some of their undesirable CNS side effects via this interaction.

Radioreceptor assay of dopamine binding activity in human serum after tiospirone administration

Tiospirone has demonstrated preclinical activities that predict utility as an antipsychotic drug which lacks the potential to produce extrapyramidal side effects. Indeed, human safety trials after single and multiple dose administration did not reveal the presence of any neurological effects. Serum samples from these studies were obtained for radioreceptor assay to determine the level of dopamine binding activity present. After a single 75 mg dose of tiospirone, demonstrable levels of dopamine binding activity were present. A variety of time points were sampled during the multiple dose study wherein subjects received 60 mg, t.i.d. for 28 days. A comparison of levels of dopamine binding activity present in serum samples taken immediately prior to dosing on various days during the course of the study suggested that steady-state was achieved within seven days with repeated administration. No further rises were seen in the remainder of the study, suggesting that further accumulation of the drug did not occur. Furthermore, hourly monitoring on the last day of drug administration did not reveal any difference, relative to the first dose, in peak levels, time to peak level appearance, or rate of disappearance of dopamine binding activity. This suggests that active metabolites do not accumulate nor is there induction of drug metabolism. Plasma levels of tiospirone were also obtained by high-performance liquid chromatography assay at similar time points. With repeated drug administration plasma tiospirone concentrations also achieved a steady state. Statistically significant increases in plasma half-life and area under the time-concentration curve were observed between day 1 and 28.(ABSTRACT TRUNCATED AT 250 WORDS)

Buspirone, a new approach to the treatment of anxiety

Anxiety has historically been treated by agents with a sedative component to their action. In the last decade or so it has been determined that gamma-aminobutyric acid (GABA) receptors may mediate the anxiolytic actions of the benzodiazepines, propanediol carbamates, barbiturates, and ethanol. However, inasmuch as these drugs have additional pharmacological properties (sedation, muscle relaxation, seizure control), the search for an anxioselective drug was continued. Buspirone appears to be such a drug. Clinical studies have clearly demonstrated the efficacy of buspirone in the treatment of generalized anxiety disorder without the ancillary pharmacology of earlier anxiolytics. Buspirone does not act on the GABA receptor. Rather, its most salient interaction with neurotransmitter receptors occurs at the 5-HT1A serotonin receptor. This action is supported by studies focused on receptor binding, anatomical localization, biochemistry, neurophysiology, and animal behavior. The recognition that action at 5-HT1A receptors may be a viable approach to the pharmacotherapy of anxiety is evidenced by the number of other agents of this class under development by a number of pharmaceutical companies.

Atypical antipsychotic agents: patterns of activity in a series of 3-substituted 2-pyridinyl-1-piperazine derivatives

A series of 3-substituted 2-pyridinyl-1-piperazine derivatives have been appended to cyclic imide groups and evaluated for their potential antipsychotic activity. The dopamine receptor affinities of these target molecules, as well as their ability to block apomorphine-induced stereotypy or reverse neuroleptic-induced catalepsy, was dependent on the lipophilic and electronic characteristics of the substituent situated on the pyridine ring. Groups with + omega and - phi values were most consistent with the desired biological profile of the target molecules, the cyano moiety being the optimum choice. Evaluation of compound 12 in a monkey model of amphetamine psychosis, and the regional selectivity it expresses for the A10 dopaminergic cell bodies in electrophysiological experiments, suggest this compound would be an atypical antipsychotic agent with few side effects.

Bone grafts in craniofacial surgery

Bone grafting or bone replacement is an integral part of craniofacial surgery. Most craniofacial surgeons prefer the use of autogenous bone; however, there are exceptions to this, because some plastic surgeons prefer the use of alloplastic implants for replacement of parts or missing segments in the craniomaxillofacial skeleton. Inlay bone grafts are useful in osteotomies because they show little resorption. Onlay bone grafts contour and balance the face aesthetically and enable the surgeon to obtain refinement and fine-tuning in all types of craniofacial reconstruction. These grafts demonstrate more resorption than inlay grafts. However, the use of onlay grafts coupled with soft-tissue shifts of galea and muscle enable the craniofacial surgeon to achieve superior results over those of surgeons primarily concerned with jaw- or tooth-related movements that do not utilize primary bone grafting as a method of augmentation. Superior results today are obtained with various methods and techniques of bone grafting, some of which have been described in this article.

Buspirone analogues. 2. Structure-activity relationships of aromatic imide derivatives

Several analogues of the novel anxiolytic buspirone were synthesized and evaluated in vivo for tranquilizing activity and their ability to reverse neuroleptic-induced catalepsy. The in vitro binding affinities of these compounds were also examined for both the alpha 1 and dopamine D2 receptor systems. The general structure-activity relationships of this series highlight compounds 17, 21, and 32 as having anticonflict activity. Each of these structures contains the 1-(2-pyrimidinyl)piperazine moiety linked by a tetramethylene chain to a variable cyclic imide moiety. Compound 32 (4,4-dimethyl-1-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-2,6- piperidinedione) was found to be equipotent with buspirone in its anxiolytic activity and was therefore selected for extensive preclinical characterization. The pharmacology of buspirone and 32 is contrasted, and the potent serotonin agonist properties of 32 are discussed with reference to its potential contribution to the anxioselective mechanism of this compound.

Three-dimensional CAT scan reconstruction--pediatric patients

Pediatric craniofacial deformities are highly complex disorders. The development of high-speed computers and related software has recently permitted three-dimensional graphics reconstruction of these deformities based on CT and NMR scan data. Such three-dimensional reconstructions are highly useful in the diagnosis, preoperative planning, and postoperative assessment of these complex deformities.

A cryptic plasmid from Nocardia orientalis NRRL 2452, a vancomycin producer

A plasmid was found in Nocardia orientalis (formerly Streptomyces orientalis). Physical characterization of the plasmid DNA indicates a size of 33.5 kb and a single cleavage site for EcoR I. The presence of plasmid, and variation in its copy member, did not directly affect vancomycin resistance or production levels. The plasmid represents the first to be isolated and characterized from a glycopeptide-producing nocardia.

Synthesis and biological evaluation of 1-(1,2-benzisothiazol-3-yl)- and (1,2-benzisoxazol-3-yl)piperazine derivatives as potential antipsychotic agents

Members of the series of title compounds were tested for potential antipsychotic activity in relevant receptor binding assays and behavioral screens. Structure-activity relationships within the series are discussed. Compound 24 (BMY 13859-1), a (1,2-benzisothiazol-3-yl)piperazine derivative, was selected for further study because of its potent and selective profile in primary CNS tests. It was active in the Sidman avoidance paradigm and blocked amphetamine-induced stereotyped behavior in dogs for up to 7 h. The compound's lack of typical neuroleptic-like effects in the rat catalepsy test and its failure to produce dopamine receptor supersensitivity following chronic administration indicate that it should not cause the movement disorders commonly associated with antipsychotic therapy. Although 24 has potent affinity for dopaminergic binding sites, its even greater affinity for serotonin receptors suggests that a serotonergic component may be relevant to its atypical profile. Compound 24 is currently undergoing clinical evaluation in schizophrenic patients.

Pharmacological and clinical effects of buspirone

Clinical trials have demonstrated that buspirone (BuSpar) is effective in the treatment of anxiety with efficacy and dosage comparable to diazepam or chlorazepate. Buspirone has a unique structure and a pharmacologic profile which distinguishes it from the benzodiazepines. Because it lacks the anticonvulsant, sedative, and muscle-relaxant properties associated with other anxiolytics, buspirone has been termed "anxioselective." Animal studies suggest that it lacks potential for abuse, and this finding is supported by clinical investigations. Further preclinical work supports the contention that buspirone lacks liability to produce physical dependence or to significantly interact with central nervous system depressants such as ethanol. Moreover, biochemical investigations have not identified any direct interaction of buspirone with the benzodiazepine-gamma-aminobutyric acid-chloride ionophore complex. Pharmacologic studies on the molecular level indicate that buspirone interacts with dopamine and serotonin receptors. Recent behavioral, electrophysiological, and biochemical studies have clearly demonstrated that early hypotheses that buspirone might be considered a neuroleptic are no longer tenable. Recent evidence indicates that other neurotransmitter systems (serotonin, norepinephrine, acetylcholine) mediate buspirone's effects. It is hoped that future studies can define the mechanism by which buspirone alleviates the clinical manifestations of anxiety.

Characterization of Streptomyces promoter sequences using the Escherichia coli galactokinase gene

A gene fusion system that uses the Escherichia coli galK gene has been developed to characterize Streptomyces transcriptional regulatory sequences. The system consists of galK-deficient Streptomyces lividans mutants and plasmids containing the E. coli galK gene with its natural ribosome-binding site and sites upstream of galK for insertion of transcription signals. Expression of the E. coli galK gene in S. lividans can be quantitated by either an enzymatic or immunoblot assay or detected by genetic complementation of an S. lividans galK- mutant. The utility of the plasmid to select, detect and assess promoter function was examined using the S. lividans XP55 and S. fradiae aph gene promoters. The potential use of the galK fusion system to isolate and characterize Streptomyces transcription signals is discussed.

Determination of functionally-relevant serum levels of MJ 13859-1 in the dog: relationship to blockade of amphetamine stereotypy

The ability of drugs to block dopamine-agonist induced stereotypy in animals has proven to be a reliable in vivo predictor of antipsychotic efficacy in man. Assessment of a drug's potency at displacing [3H]spiperone from rat striatal membranes is an in vitro test which also has predictive validity for antipsychotic actions. Methods are described for assessing stereotyped behavior in the dog, and for measuring the ability of serum samples taken from treated animals at behaviorally interesting time points, to displace [3H]spiperone from washed synaptic membranes of rat striata. In these studies, oral administration of the potential antipsychotic agent MJ 13859-1 blocked amphetamine-induced stereotyped behavior in the dog for 6 hours. This behavioral effect was accompanied by sustained serum levels of [3H]spiperone displacing moieties derived from MJ 13859-1.

Improved genetically modified Escherichia coli strain for prescreening antineoplastic agents

Clinical experience suggests that drugs that interact with and damage DNA are useful in cancer chemotherapy (H. Umezawa , p. 43-72, in V. T. DeVita , Jr., and H. Busch [ed.], Methods in Cancer Research; Cancer Drug Development, vol. XVI, 1979). Prescreening systems for antitumor agents in natural products require assays that are exquisitely sensitive, since the active components are often produced in quantities of micrograms per milliliter or less. One assay used to identify agents that interact with DNA is the biochemical induction assay, utilizing Escherichia coli BR 513 (R. K. Elespuru and R. J. White, Cancer Res. 43:2819-2830, 1983). In this paper we describe a genetic modification of strain BR 513 that displays an expanded spectrum of activity. This strain may provide an improved prescreen for detecting natural products that interact with DNA.

Neuropharmacology of buspirone

Buspirone is a clinically effective anxiolytic with a unique structure and pharmacology which distinguishes it from the benzodiazepines. It has been termed anxioselective because it lacks anticonvulsant, sedative, or muscle-relaxant properties. Preclinical evidence suggests it lacks potential for abuse or physical dependence and interacts minimally with CNS depressants such as alcohol. Rather than working through traditional benzodiazepine mechanisms, buspirone affects diverse aspects of the brain's neurochemical circuitry. For example, it exerts potent influences on the nigrostriatal and mesolimbic dopamine systems, the dorsal raphe serotonergic system, and the locus coeruleus noradrenergic system. Although without direct receptor interaction, potentiation of cholinergically mediated behavior and involvement with GABAergic neurotransmission have also been demonstrated.

Gene cloning in the actinomycetes

The production of antibiotics by soil-borne micro-organisms, the actinomycetes, has considerable economic importance. The manipulation of antibiotic producers has become a prime target for the application of recombinant DNA technology. Certain technical requirements have had to be met for gene cloning to be successful in the actinomycetes. These requirements, including the development of cloning vectors and transformation procedures, have been satisfied, in part, for some members of the Streptomyces genus. Some problems including sequence rearrangement and stability of plasmid maintenance are now being recognized. A number of genes have been cloned in Streptomyces and some preliminary results characterizing the gene for a Streptomyces-derived beta-galactosidase-like activity were described.

Ethanol Production by Saccharomyces cerevisiae Immobilized in Hollow-Fiber Membrane Bioreactors

Saccharomyces cerevisiae ATCC 4126 was grown within the macroporous matrix of asymmetric-walled polysulfone hollow-fiber membranes and on the exterior surfaces of isotropic-walled polypropylene hollow-fiber membranes. Nutrients were supplied and products were removed by single-pass perfusion of the fiber lumens. Growth of yeast cells within the macrovoids of the asymmetric-walled membranes attained densities of greater than 10 10 cells per ml and in some regions accounted for nearly 100% of the available macrovoid volume, forming a tissue-like mass. A radial distribution of cell packing existed across the fiber wall, indicating an inadequate glucose supply to cells located beyond 100 μm from the lumen surface. By comparison, yeast cell growth on the exterior surfaces of the isotropic-walled membranes resulted in an average density of 3.5 × 10 9 viable cells per ml. Ethanol production by reactors containing isotropic polypropylene fibers reached a maximum value of 26 g/liter-h based on the total reactor volume. Reactor performance depended on the fiber packing density and on the glucose medium flow rate and was limited by low nutrient and product transport rates. The inhibition of ethanol production and the reduction in fermentation efficiency arose primarily from the accumulation of CO 2 gas within the sealed reactor shell space.

Alignment of genetic and restriction maps of the photosynthesis region of the Rhodopseudomonas capsulata chromosome by a conjugation-mediated marker rescue technique

The restriction map of a 46-kilobase fragment of the Rhodopseudomonas capsulata chromosome was aligned with the genetic map of the photosynthesis region of that chromosome by a marker rescue technique. Marker rescue was effected by mobilization of vectors bearing fragments of R. capsulata DNA from Escherichia coli to a set of R. capsulata mutants. Plasmids pDPT51 and pDPT55 were constructed to mediate the intergeneric mobilization of pBR322 derivatives, and a mutant of R. capsulata with improved intergeneric recipient activity was isolated. Four previously unmapped genes affecting bacteriochlorophyll synthesis and two genes affecting photochemical reaction center synthesis have been located by marker rescue. Some of the fragments of R. capsulata DNA are capable of vector-independent complementation, implying that promoters are located on these fragments. Other fragments complement only in one orientation of insertion in the vector, implying transcription from promotors on the vectors and thereby fixing the direction of transcription for those fragments. Still other fragments of DNA show rescue only via recombination between homologous plasmid-borne DNA fragments and chromosomal mutations. The physical dimensions of the genetic map are 3.0 megadaltons per map unit, which agrees with previous estimates based on the size of the R. capsulata gene transfer agent.

Physical characterization of plasmids isolated from Streptosporangium

Plasmids were isolated from two species of Streptosporangium by CsCl-ethidium bromide equilibrium density gradient centrifugation. A plasmid isolated from S. brasiliense, designated pSgB-1, was characterized by electron microscopy and agarose gel electrophoresis. The pSgB-1 plasmid is a closed circular DNA molecule of 9.4 X 10(6) Da. A restriction endonuclease map was generated and unique cleavage sites were found for EcoRI, ClaI, XbaI, and MstII. Another plasmid, pSgV-1, isolated from S. viridognriseum, has an estimated Mr of 54 X 10(6). The pSgB-1 plasmid is phenotypically cryptic but an unusual phenotypic trait, resembling phage plaques, may be associated with the S. viridogriseum plasmid pSgV-1.

[3H]tetrahydrotrazodone binding. Association with serotonin binding sites

High (17 nM) and low (603 nM) affinity binding sites for [3H]tetrahydrotrazodone ([3H] THT), a biologically active analogue of trazodone, have been identified in rat brain membranes. The substrate specificity, concentration, and subcellular and regional distributions of these sites suggest that they may represent a component of the serotonin transmitter system. Pharmacological analysis of [3H]THT binding, coupled with brain lesion and drug treatment experiments, revealed that, unlike other antidepressants, [3H] THT does not attach to either a biogenic amine transporter or serotonin binding sites. Rather, it would appear that [3H]THT may be an antagonist ligand for the serotonin binding site. This probe may prove of value in defining the mechanism of action of trazodone and in further characterizing serotonin receptors.

Buspirone analogues. 1. Structure-activity relationships in a series of N-aryl- and heteroarylpiperazine derivatives

A series of analogues of buspirone was synthesized in which modifications were made in the aryl moiety, alkylene chain length, and cyclic imide portion of the molecule. These compounds were tested in vitro for their binding affinities to rat brain membrane sites labeled by either the dopamine antagonist [3H]spiperone or the alpha 1-adrenergic antagonist [3H]WB-4101. Compounds were also tested in vivo for tranquilizing properties and induction of catalepsy. Potency at the [3H]spiperone binding site was affected by alkylene chain length and imide portion composition. Nonortho substituents on the aryl moiety had little effect on [3H]spiperone binding affinity. Structure-activity relationships of ortho substituents demonstrated only modest correlations between the receptor binding data and physical parameters of the substituents. The complex nature of the drug-receptor interactions may be understood in terms of the fit of buspirone to a hypothetical model of the dopamine receptor.

Pharmacology and neurochemistry of buspirone

Biochemically, buspirone is unlike the benzodiazepines in that it neither stimulates nor inhibits 3H-benzodiazepine binding, does not affect the influence of GABA or halide anion on 3H-benzodiazepine binding, and does not interfere with GABA binding or uptake. Buspirone lacks anticonvulsant activity, interacts minimally with CNS depressants, and does not cause muscle relaxation. Its tranquilizing activity is characterized by the ability to (1) tame aggressive rhesus monkeys, (2) block conditioned avoidance responding in the rat, (3) inhibit shock-induced fighting in the mouse, and (4) attenuate shock-induced suppression of drinking in the rat. In vitro binding experiments indicate that buspirone lacks significant activity at several binding sites. It appears to interact only with the dopaminergic system and possesses properties that are similar to both dopamine agonists and dopamine antagonists.

Dopamine and antianxiety activity

Clinical trials have indicated that buspirone (Buspar) is effective in the treatment of anxiety with efficacy and dosage comparable to diazepam. Until recently it has been thought that antianxiety drugs must alter benzodiazepine receptor binding in vitro. However, buspirone lacks any structural similarity to te benzodiazepines and does not interact with the benzodiazepine/gamma-aminobutyric acid (GABA) axis. Specifically, buspirone neither stimulates nor inhibits [3H]benzodiazepine binding, does not affect the influence o GABA or halide anions on benzodiazepine binding, and does not interfere with GABA binding or uptake. Behavioral testing has revealed that buspirone does not produce muscle weakness, does not control seizures, does not potentiate the impairment of psychophysiological function or lethality produced by administration of CNS depressants, does not produce sedation/hypnosis and does not appear to possess any abuse potential or liability for physical dependence. Thus, buspirone has been termed an anxioselective agent. Buspirone appears to only interact with the dopaminergic system with reasonable potency and exhibits properties of both a dopamine agonist and a dopamine antagonist. This suggests that dopamine is implicated in the etiology and expression of anxiety. A discussion of this implication is presented with a review of the clinical efficacy of nonbenzodiazepine drugs, especially dopamine agonists and dopamine antagonists, in the management of anxiety. In addition, neuropharmacological studies which have investigated the role of dopamine in animal models of anxiety are considered. Finally, the multiplicity of dopamine receptors and their regional localization in the brain are considered in the formulation of an hypothesis which features a role for the dopaminergic agents in the pharmacotherapy of anxiety.

Effects of guanine nucleotides on CNS neuropeptide receptors

The effect of nucleotides on central nervous system neuropeptide receptor binding was investigated. The guanine nucleotides, guanosine-5'-triphosphate and guanylyl-5'-imidodiphosphate, significantly inhibited the binding of radiolabeled vasoactive intestinal polypeptide but not that of [Tyr4]bombesin to rat brain membranes. Vasoactive intestinal polypeptide binding was inhibited by guanine nucleotides in a dose-dependent manner. Using a 20 microM dose, 60% of the specific vasoactive intestinal polypeptide binding was inhibited by guanylyl-5'-imido-diphosphate, which was more potent than guanosine-5'-triphosphate, whereas other nucleotides were not effective. This reduction in binding was a consequence of lower affinity of the receptor for vasoactive intestinal polypeptide, which in turn resulted from an increased rate of dissociation.

The interaction of trazodone with rat brain muscarinic cholinoceptors

The muscarinic receptor binding of trazodone, a new nontricyclic antidepressant, was compared with established tricyclic antidepressants. The ability to inhibit the binding of [3H]-quinuclidinyl benzilate in vitro was used for comparing atropine-like effects. Trazodone was found to have essentially no activity at the muscarinic acetylcholine binding site in comparison to the tricyclic antidepressants.

Lack of effect of neurotransmitters on cyclic AMP phosphodiesterase activity in an insect CNS

The inhibition of cyclic nucleotide phosphodiesterase from the nerve cord of Manduca sexta was studied using theophylline as a model compound. 11 putative neurotransmitters had no effect on enzyme activity.

Vasoactive intestinal polypeptide: specific binding to rat brain membranes

The binding of radiolabeled vasoactive intestinal polypeptide (VIP) to rat brain membranes was investigated. Specific binding of 125I-labeled VIP was reversible and saturable (Bmax = 2.2 pmol/g of wet tissue). Brain membranes exhibited a high affinity for 125I-labeled VIP (KD = 1 nM) at a single class of noninteracting sites. Binding of 125I-labeled VIP paralleled its immunohistochemical localization, being enriched in cerebral cortex, hippocampus, striatum, and thalamus, with the notable exception of the hypothalamus, which had low levels of binding. The density of sites was greater in synaptosomal fractions relative to mitochondrial or nuclear fractions. Secretin and partial sequences of it and VIP inhibited binding to brain membranes with an order of potency similar to that found in other systems. The findings suggest the existence of a unique new class of brain receptors.

Structural and functional analysis of cloned DNA segments containing the replication and incompatibility regions of a miniplasmid derived from a copy number mutant of NR1

A 1.45-megadalton segment of DNA cloned from a miniplasmid derived in vivo from a copy number mutant of the R plasmid NR1 has been shown to contain all functions essential for incompatibility and autonomous plasmid replication in Escherichia coli. Specific endonuclease cleavage sites within this DNA segment that localize functions required for replication have been mapped. A 0.45-megadalton fragment that specifies the FII incompatibility of NR1 has been identified within the replication region, and DNA fragments containing this incompatibility region, but lacking other functions required for replication, have been cloned.

Generation of miniplasmids from copy number mutants of the R plasmid NR1

Small, closed circular deoxyribonucleic acid molecules, called miniplasmids, were observed in Escherichia coli harboring copy number mutants of the R plasmid NR1 after growth in medium containing tetracycline. The level of tetracycline resistance conferred by the copy mutant plasmids was lower (3 to 6 microgram/ml) than that conferred by NR1 (100 MICROGRAM/ML). The presence of the miniplasmid enhanced the level of tetracycline resistance conferred by the copy mutant. Miniplasmids of molecular weights 4 X 10(6) to 13 X 10(6) were found. They carried no antibiotic resistance markers and could be eliminated by growth in the presence of chloramphenicol and/or streptomycin-spectinomycin. Studies with the restriction endonucleases EcoRI and Sal I indicated that the miniplasmids are derived from the region of the copy mutant plasmids that contains the origin for replication of the resistance transfer factor. There were approximately 12 copies of the miniplasmid per chromosome, compared with 3 and 6 copies of the copy mutants of NR1. The miniplasmids appeared to be incompatible with the copy mutant plasmids.

Method for obtaining more-accurate covalently closed circular plasmid-to-chromosome ratios from bacterial lysates by dye-buoyant density centrifugation

A method that gives high recovery of deoxyribonucleic acid (DNA) from crude bacterial lysates using ethidium bromide-cesium chloride density gradient centrifugation is presented. After Pronase digestion and shearing of the lysate, essentially 100% recovery of chromosomal DNA and a reproducible recovery of covalently closed circular (CCC) plasmid DNA is obtained for a specific plasmid in a given strain. This method should be useful for comparing the CCC plasmid/chromosome ratio of various plasmid-host combinations.

Races of the Barley Root-Knot Nematode, Meloidogyne naasi. III. Reproduction and Pathogenicity on Creeping Bentgrass

Reproduction and pathogenicity of the five known races of Meloidogyne naasi on two selections of creeping bentgrass were compared. Toronto C-15 was a host for Races 3, 4 and 5, whereas Northmoor 9 supported reproduction of all five races. Differences in susceptibility and population increase demonstrated that the races could be separated by degree of reproduction on the two selections. Root weights generally were unaffected. Based on cumulative dipping weights, all but Race 1 were pathogenic on at least one of the selections; Race 3 stunted top growth of both. Slight differences in degree of pathogenicity, associated with final populations, were not broad enough to be useful in race separation.

Races of the Barley Root-Knot Nematode, Meloidogyne naasi. II. Developmental Rates

The developmental rates of the five newly designated races of Meloidogyne naasi were compared on barley, oat and sorghum. Races 1, 2, 3 and 4 developed and reproduced on both barley and oat but not on sorghum. Race 5 developed and reproduced readily on sorghum but poorly on oat. A more rapid rate of development of Race 5 on both barley and sorghum than that of other races on barley demonstrated that Race 5 has a shorter life cycle than do Races 1-4.

Races of the Barley Root-Knot Nematode, Meloidogyne naasi. I. Characterization by Host Preference

The host preferences of populations of Meloidogyne naasi from England, California, Illinois, Kentucky and Kansas were compared. Among 22 plant species tested, most were hosts for isolates of all five populations; crabgrass was added to the list of known hosts. Differential reactions of isolates on creeping bentgrass, curly dock, sorghum, and common chickweed demonstrated the existence of at least five physiological races within M. naasi. The known races are numerically designated and characterized.

Interaction of Meloidogyne naasi, Pratylenchus penetrans, and Tylenchorhynchus agri on Creeping Beentgrass

The pathogenicity and interactions of Meloidogyne naasi, Pratylenchus penetrans, and Tylenchorhynchus agri on 'Toronto C-15' creeping bentgrass, Agrostis palustris, was studied in a long-term greenhouse experiment. Based on dry weights of roots and clippings, M. naasi alone and in all combinations with P. penetrans and T. agri was highly pathogenic to creeping bentgrass. P. penetrans and T. agri alone and in combination inhibited root growth but adversely affected top growth only when the two were co-inoculated. In combination, the effects of each species on top growth were additive, with M. naasi the dominant pathogen. Creeping bentgrass was an excellent host for M. naasi and T. agri, but a poor host for P. penetrans. T. agri inhibited population increase of M. naasi, indicating nematode-nematode competition, but neither T. agr/ nor P. penetrans was affected by any of the combinations.

Histopathogenesis of Galls Induced by Meloidogyne naasi in Wheat Roots

Histopathogenesis of galls induced by Meloidogyne naasi in wheat roots was studied. Large numbers of larvae penetrated wheat root tips within 24 hr; larvae migrated both inter- and intracellularly, causing cortical hypertrophy. Giant cells were formed in the stele around the head of each nematode within 4 to 5 days. Initial pathological alterations in giant cell formation consisted of hypertrophy of protophloem and protoxylem cells, their nuclei and nucleoli. Giant ceils contained 2 to 8 agglomerated multinucleolate nuclei. Synchronous mitotic divisions were first observed 9 days after inoculation. After 21 days, giant cells became highly vacuolate. Observations 40 days after inoculation revealed a complete degeneration of cell contents in many giant cells but their thick walls remained intact. Abnormal xylem completely surrounded the degenerated or partially degenerated giant cells.

Sexual Attraction and Mating Patterns in Cylindrocorpus longistoma and C. curzii (Nematoda: Cylindrocorporidae)

Females of Cylindrocorpus longistoma and C. curzii excrete attractants which probably function to bring the sexes together before mating. Intraspecific and interspecific heterosexual and homosexual pairing experiments showed the attractants to be species specific as well as sex specific. Observations on mating behavior support the hypothesis that sexual attraction and copulation require independent stimuli.