Presynaptic regulation of dopaminergic transmission in the striatum

1. In vitro studies have indicated that several transmitters present in the striatum can regulate presynaptically the release of dopamine (DA) from nerve terminals of the nigrostriatal DA neurons. 2. The receptors involved in these local regulatory processes are located or not located on DA nerve terminals. 3. Recent in vivo investigations have demonstrated that the corticostriatal glutamatergic neurons facilitate presynaptically the release of DA and have allowed the analysis of the respective roles of presynaptic events and nerve activity in the control of DA transmission.     

Detection and characterization of "chimeric" yeast artificial chromosome clones by fluorescent in situ suppression hybridization.

"Chimeric" yeast artificial chromosomes (YACs) are clones containing two or more noncontiguous segments of DNA and represent the most common artifact found in total genomic YAC libraries currently used for large-scale genome mapping. These YACs create spurious mapping information that complicates the construction of YAC contigs and leads to erroneous maps during chromosome walks. The presence of these artifactual clones necessitates laborious and time-consuming characterization of each isolated YAC clone, either by comparison of the physical map of the YAC with the corresponding source genomic DNA, or by demonstrating discrepant chromosomal origins for the two ends of the YAC by hybridization or polymerase chain reaction (PCR). Here, we describe a rapid and sensitive method for the assessment of YAC colinearity by fluorescence in situ suppression hybridization (FISSH) by utilizing fluorescein-12-dUTP for labeling YAC clones. We have analyzed 51 YACs and found that 43% (22 out of 51) are chimeric and significantly larger (302 kb) than colinear ones (228 kb). One of the 51 YAC clones (2%) examined contains portions of three chromosomes and 2 (4%) seem to map to a chromosome different than that of the identifying STS. FISSH analysis offers a straightforward visualization of the entire YAC insert on the chromosomes and can be used to examine many YACs simultaneously in few days.     

Germacranolides from Schkuhria anthemoidea

The isolation of eucannabinolide and three new sesquiterpene lactones from Schkuhria anthemoidea is reported. The structures and stereochemistries of the new compounds were established by chemical and spectroscopic means. The structure of santhemoidin B was confirmed by X-ray crystallography.     

Sesquiterpene lactones from Viguiera species

Viguiera eriophora yielded the sesquiterpene lactones erioflorin, acetylerioflorin and 17,18-dehydroviguiepinin, which was correlated with tetrahyd     

Anti-inflammatory constituents of Mortonia greggii Gray

A new phytochemical study of Mortonia greggii (Celastraceae) afforded four friedelan derivatives (1-4), three lupanes (5-7), retusine (8), two esterified polyhydroxyagarofurans (9-10), mortonin C (11) and photomortonin C (12). The anti-inflammatory activity on carrageenan and 12-O-tetradecanoylphorbol-13-acetate induced models of inflammation, as well as the ability to inhibit the nitric oxide (NO) produced by lipopolysaccharide-stimulated mouse peritoneal macrophages were evaluated for the main metabolites. Our results showed that the friedelan dehydrocanophyllic acid methyl ester (1) exhibits an anti-inflammatory effect which could be related to an inhibition of prostaglandin and NO production. The activity of lupeol (5), 29-hydroxylupeol (6) and 29-hydroxylupenone (7) might be involved with the prostanoid synthesis. The presence of the hydroxy groups in 6 appears to be important for activity. The edema inhibition capacity of retusine (8) could be related to a reduction of the prostaglandin production. The agarofuran derivative 10 is an NO inhibitor whose activity is probably not involved in the synthesis of prostaglandins.     

Flutter discrimination: neural codes,perception, memory and decision making

Recent studies combining psychophysical and neurophysiological experiments in behaving monkeys have provided new insights into how several cortical areas integrate efforts to solve a vibrotactile discrimination task. In particular, these studies have addressed how neural codes are related to perception, working memory and decision making in this model. The primary somatosensory cortex drives higher cortical areas where past and current sensory information are combined, such that a comparison of the two evolves into a behavioural decision. These and other observations in visual tasks indicate that decisions emerge from highly-distributed processes in which the details of a scheduled motor plan are gradually specified by sensory information.     

Endoscopic foreheadplasty: a histologic comparison of periosteal refixation after endoscopic versus bicoronal lift

Endoscopic brow lift techniques using temporary fixation rely on rapid readherence of the periosteum to calvarial bone. Little is known about the histologic events that occur during the early postoperative period after these procedures. An animal study was designed to compare and contrast periosteal fixation to bone and unelevated periosteum, with endoscopic and bicoronal brow lift techniques. One method of temporary fixation is the use of absorbable (polylactic/polyglycolic acid copolymer) LactoSorb screws; a histologic analysis of implanted LactoSorb screws was also performed. Sixteen rabbits underwent brow lifts; eight underwent endoscopic brow lift and fixation with LactoSorb screws without skin excision, and another eight underwent traditional bicoronal brow lift with skin excision and closure under tension. Animals were killed 1, 2, 6, and 12 weeks after the procedures were performed to evaluate the interaction of periosteum and bone and the normal, unelevated periosteum/calvarium interface at a site distant from the operative area. Histologic specimens were examined for the degree of apposition of periosteum to bone and for any fibrous or bony reaction at this interface. Histologic analysis showed various degrees of periosteal fibrosis and fixation to calvarial bone. After an initial phase of minimal periosteal adherence and moderate inflammation, the periosteum became progressively more adherent to bone in both groups, with no significant differences between treatment groups in rates of fixation. Fixation required at least 6 weeks. LactoSorb screws were surrounded by an area of mild inflammation and were progressively hydrolyzed and digested. Periosteal fixation increases over time for bicoronal and endoscopic brow lifts with minimal differences between the two techniques. With this animal model, periosteal adherence to calvarium requires at least 6 weeks with complete adherence by 12 weeks. In addition, the use of absorbable fixation screws seems to be both effective and well tolerated. The histologic changes associated with periosteal healing observed in this study suggest that permanent or semipermanent fixation may improve the accuracy and early postoperative maintenance of forehead advancement.     

Ejaculate and type of freezing extender affect rates of fertilization of horse oocytes in vitro

In vitro fertilization (IVF) was performed on in vitro-matured equine oocytes in three experiments. Frozen-thawed sperm were prepared using swim-up separation and heparin treatment. In Experiment 1, fertilization was achieved with sperm from only one frozen ejaculate of four obtained from the same stallion. Within this ejaculate, fertilization rates were higher with fresh media, as compared to media held for 6-8 days before use (39.6% versus 7.3%, respectively; P<0.001). The type of bovine serum albumin used affected fertilization rates (4% versus 39.6%; P<0.001). To determine if IVF rates were influenced by factors associated with the freezing process (Experiment 2), a single ejaculate from a second stallion was frozen using eight variations in timing of steps in the freezing protocol. There were no differences among treatments in fertilization rates (range, 0-3%). In Experiment 3, fertilization rates of semen frozen in an extender containing 21.5% egg yolk were lower than fertilization rates of semen from the same ejaculate but frozen with a 3% egg-yolk extender (0% versus 15%, respectively; P<0.01). We inferred that rates of equine IVF with frozen-thawed sperm were influenced by ejaculate, the composition and age of the media used, and freezing extender. To our knowledge, this is the first report of ejaculate or extender differences affecting in vitro fertilization in this species. These factors may help to explain the great variability in fertilization rates reported with equine IVF, both among and within laboratories.