Effects of alprazolam and clonidine on carbon dioxide-induced increases in anxiety ratings in healthy human subjects

In order to investigate possible neurobiologic mechanisms underlying carbon dioxide-induced anxiety, the effects of oral alprazolam 0.75 mg and intravenous clonidine 2 mcg/kg on CO2-induced increases in ratings of subjective anxiety, pulse rate, and ventilation were measured in healthy human subjects. Pretreatment with alprazolam but not with clonidine significantly reduced the CO2-induced increase in ratings of anxiety. Neither drug altered CO2-induced increases in pulse rate or ventilatory responses. Clonidine did produce potent sedative and hypotensive effects. The behavioral data suggest that the mechanisms through which CO2 induces anxiety-like effects involve neural systems regulated by benzodiazepine receptors and, secondly, that they appear not to require normal functioning of noradrenergic systems. Carbon dioxide may provide a useful model system for identification of new drugs with anxiolytic properties.     

Osteoarthritis, calcium pyrophosphate deposition disease, and osseous infection in Old World primates.

Uncertainties as to the nature and implications of osteoarthritis and calcium pyrophosphate deposition disease (CPPD) in primates were subject to critical review through examination of 153 prosimians and 1,250 Old World non-prosimian primates. Osteoarthritis, calcium pyrophosphate deposition disease, and infectious arthritis/osteomyelitis were relatively rare phenomena, affecting only 1.7% and 2.5%, respectively, of free-ranging prosimians and other Old World non-prosimian primates. Frequency of infection in Indri and Presbytis appears to reflect a unique susceptibility or exposure. Papio may have a unique predisposition to CPPD. The dichotomy (frequency and joint distribution) between free-ranging and artificially restrained animals suggests caution in interpretation of osteoarthritis or CPPD in non-free-ranging animals.     

Enhancement of gamma-glutamylcysteine synthetase mRNA in rat kidney by methyl mercury.

Glutathione (GSH), a major cellular antioxidant, is elevated 2- to 3-fold in kidneys of rats during prolonged treatment with mercury as methyl mercury hydroxide (MMH). Increased renal GSH is accompanied by a dose- and time-related elevation in the relative abundance of mRNA hybridizable to a cDNA probe which encodes renal gamma-glutamylcysteine synthetase (GCS), the rate-limiting enzyme in GSH synthesis. Renal GCS mRNA is maximally elevated 4.4-fold at 3 weeks following initiation of MMH treatment. Enhancement of GSH and GCS mRNA content corresponds to a relative sparing of renal cells from oxidative tissue damage during MMH exposure. These observations suggest that increased synthesis of GSH at the genetic level occurs as an initial adaptive response to mercury-induced oxidative stress in kidney cells.     

Cloning of Bacteroides fragilis plasmid genes affecting metronidazole resistance and ultraviolet survival in Escherichia coli

Since reduced metronidazole causes DNA damage, resistance to metronidazole was used as a selection method for the cloning of Bacteroides fragilis genes affecting DNA repair mechanisms in Escherichia coli. Genes from B. fragilis Bf-2 were cloned on a recombinant plasmid pMT100 which made E. coli AB1157 and uvrA, B, and C mutant strains more resistant to metronidazole, but more sensitive to far uv irradiation under aerobic conditions. The loci affecting metronidazole resistance and uv sensitivity were linked and located on a 5-kb DNA fragment which originated from the small 6-kb cryptic plasmid pBFC1 present in B. fragilis Bf-2 cells.     

Evidence for two Ca2(+)-mobilizing purinoceptors on rat hepatocytes.

Aequorin measurements of cytosolic free Ca2+ in single rat hepatocytes show that ADP and ATP, thought to act through the same P2Y purinoceptor, elicited very different responses in the majority of cells tested. ADP invariably induced transients of short duration (approx. 9 s), whereas ATP induced either similar transients or transients with a much longer duration (approx. 49 s). We explain this variability in terms of two separate purinoceptors on rat hepatocytes, one of which responds to either ATP or ADP to generate free-Ca2+ transients of short duration, and the other responds to ATP only, with transients of longer duration.     

Transformation and pp60v-src autophosphorylation correlate with SHC-GRB2 complex formation in rat and chicken cells expressing host-range and kinase-active, transformation-defective alleles of v-src.

The biochemical properties of several pp60v-src substrates believed to participate in src-mediated transformation were examined in cells expressing a kinase-active, transformation-defective v-src allele (v-src-F172 delta/Y416F) and its parental allele, v-src-F172 delta, a host-range--dependent allele that transforms chicken cells to a fusiform morphology, but does not transform rat cells. Because pp60v-src-F172 delta is dependent on autophosphorylation for transforming ability, these alleles provide a unique opportunity to examine the role of pp60v-src autophosphorylation in regulating substrate interactions. Increased pp125FAK tyrosine phosphorylation and high levels of pp60v-src-associated phosphotidylinositol-3' kinase activity were detected specifically in chicken cells exhibiting round, refractile transformation but not in cells transformed to a fusiform morphology. Increased pp125FAK kinase activity, but not increased pp125FAK tyrosine-phosphorylation correlated with pp60v-src autophosphorylation and increased anchorage-independent growth. Thus, pp125FAK and PI3'K may participate in morphological transformation by v-src. Furthermore, association of phosphorylated SHC with the adapter GRB2 correlated with increased anchorage-independent growth (and autophosphorylation) in both rat and chicken cells independent of the morphological phenotype induced. Therefore, host-range dependence for transformation may be regulated through association of SHC with GRB2, thus implicating SHC as a crucial substrate for src-dependent transformation.     

Regiospecificity of chlorophenol reductive dechlorination by vitamin b(12s)

Vitamin B(12), reduced by titanium (III) citrate to vitamin B(12s), catalyzes the reductive dechlorination of chlorophenols. Reductive dechlorination of pentachlorophenol and of all tetrachlorophenol and trichlorophenol isomers was observed. Reaction of various chlorophenols with vitamin B(12) favored reductive dechlorination at positions adjacent to another chlorinated carbon, but chlorines ortho to the hydroxyl group of a phenol were particularly resistant to reductive dechlorination, even if they were also ortho to a chlorine. This resulted in a reductive dechlorination pattern favoring removal of para and meta chlorines, which differs substantially from the pattern exhibited by anaerobic microbial consortia.     

Autonomous replication of foreign DNA in Histoplasma capsulatum: role of native telomeric sequences.

Genetic transformation of the dimorphic pathogenic fungus Histoplasma capsulatum can result in chromosomal integration of the transforming DNA or the generation of multicopy linear plasmids carrying the transforming DNA. We showed previously that Escherichia coli plasmids do not replicate autonomously in H. capsulatum without significant modifications, one of which is the in vivo addition of Histoplasma telomeres at the termini of linear DNA. To address the requirements for autonomous replication in H. capsulatum, we constructed a circular E. coli plasmid containing adjacent inverted stretches of Histoplasma telomeric repeats separated by a unique restriction site. The linearized plasmid bearing telomeric termini was maintained in H. capsulatum without modification other than the addition of more telomeric sequence. We recovered the original plasmid in E. coli after removal of the telomeric termini by using engineered restriction sites. Thus, no special Histoplasma modification or sequence other than the telomeres was needed for autonomous replication in H. capsulatum. Additionally, this plasmid provides a shuttle vector that replicates autonomously in E. coli (as a circular plasmid) and in H. capsulatum (as a linear plasmid).     

Bioactivity and molecular modelling of diphenylsulfides and diphenylselenides

Bis(2-bromo-4,5-dimethoxyphenyl)sulfide (5) and bis(2-bromo-4,5-dimethoxyphenyl) selenide (7) have been shown to block cells in the G2/M phase of the cell cycle, whereas the debromo (4, 6) equivalents do not. The dibromoselenide (7) is cytotoxic to tumour cells in vitro and has been shown to increase the mitotic index of treated cells. These biological effects are consistent with disruption of the mitotic apparatus. This agent does not inhibit microtubule assembly in vitro, but does bind to tubulin. Molecular modelling of these structures indicates that their spatial and electronic structures may make an important contribution to the biological activity.