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C A Warren

Publications and source records attributed to C A Warren.

At least 19 recordsLinked to original sources
PubMed2001

Effects of 12-h tobacco deprivation on event-related potentials elicited by visual smoking cues.

RATIONALE: A cigarette smoker's reactivity to smoking cues, or cue-reactivity, traditionally has been indexed by self-report and/or measures of autonomic nervous system activity. Recent evidence suggests that measures of central nervous system activity in the form of event-related brain potentials (ERPs) may also index cue-reactivity in smokers. OBJECTIVE: The present study sought to confirm the sensitivity of ERPs to smoking cues and to investigate the question of whether 12 h of smoking deprivation would enhance ERP cue-reactivity to such stimuli. METHODS: Scalp ERPs were recorded to 80 smoking-related pictures and 80 neutral pictures, i.e., similar pictures with a nonsmoking theme, in 19 tobacco-deprived smokers, 17 nondeprived smokers, and 19 nonsmokers. RESULTS: Smokers' N300 amplitudes over fronto-central scalp were larger to neutral than to smoking-related stimuli, thus reflecting N300 smoking cue-reactivity. N300 cue-reactivity was greater for deprived than for nondeprived smokers. Smokers' P300 values were greater to smoking-related than to neutral stimuli, particularly over the centro-parietal area; however, nonsmokers also showed a P300 main effect to smoking cues. Smoking deprivation did not affect P300 cue-reactivity, nor did deprivation affect self-reported urges to smoking relative to neutral cues. CONCLUSIONS: These data confirm the sensitivity of ERPs to tobacco cues in smokers and suggest, additionally, that the cue-reactivity of the N300 component is modulated by smoking deprivation. N300 cue-reactivity may reflect an internally generated priming of the semantic network related to the smokers' need states. Stimulus-category differences in P300 may reflect cue-reactivity in smokers and/or nonaddiction-specific factors in both smokers and nonsmokers.

Adult↗
PubMed1999

Event-related brain potentials as indicators of smoking cue-reactivity.

OBJECTIVE: Reactivity to smoking cues, shown previously by autonomic and self-report variables, was investigated in smokers and nonsmokers using event-related brain potentials (ERPs). METHODS: Average ERPs to 20 color pictures of people smoking and 20 neutral pictures depicting nonsmoking themes, randomly mixed with 4 repetitions/stimulus, were measured from 20 light-moderate smokers and 18 nonsmokers, following a stressor. Smoker status and stimulus type effects on ERPs and principal components factor scores (FS) were tested by repeated-measures ANOVAs. RESULTS: Smokers' N268 showed significant medial and midline smoking cue-reactivity (ERP to smoking-related minus neutral stimuli); while a P300-like, P412, showed significant smoking cue-reactivity over medial and left hemisphere scalp. FS analyses confirmed most of the foregoing. P412 smoking cue-reactivity was correlated with unpleasantness-pleasantness cue-reactivity but not with urge-to-smoke cue-reactivity. Nonsmokers' N268 stimulus differences were not significant, but significant P412 stimulus effects (unconfirmed by FS analyses) were found in central-to-posterior and in left parietal-temporal areas. CONCLUSIONS: Smokers' N268 is identified with a process detecting stimuli incongruent with tobacco-addicted states; and P412 smoking cue-reactivity is discussed in terms of an automatic, perceptual-categorization system, consistent with Tiffany's drug-use and Johnson's P300 models. Implications of ERP smoking cue-reactivity for study of tobacco and other addictions are discussed.

Adult↗
PubMed1998

Transcriptionally active MuDR, the regulatory element of the mutator transposable element family of Zea mays, is present in some accessions of the Mexican land race Zapalote chico.

To date, mobile Mu transposons and their autonomous regulator MuDR have been found only in the two known Mutator lines of maize and their immediate descendants. To gain insight into the origin, organization, and regulation of Mutator elements, we surveyed exotic maize and related species for cross-hybridization to MuDR. Some accessions of the mexican land race Zapalote chico contain one to several copies of full-length, unmethylated, and transcriptionally active MuDR-like elements plus non-autonomous Mu elements. The sequenced 5.0-kb MuDR-Zc element is 94.6% identical to MuDR, with only 20 amino acid changes in the 93-kD predicted protein encoded by mudrA and ten amino acid changes in the 23-kD predicted protein of mudrB. The terminal inverted repeat (TIR) A of MuDR-Zc is identical to standard MuDR; TIRB is 11.2% divergent from TIRA. In Zapalote chico, mudrA transcripts are very rare, while mudrB transcripts are as abundant as in Mutator lines with a few copies of MuDR. Zapalote chico lines with MuDR-like elements can trans-activate reporter alleles in inactive Mutator backgrounds; they match the characteristic increased forward mutation frequency of standard Mutator lines, but only after outcrossing to another line. Zapalote chico accessions that lack MuDR-like elements and the single copy MuDR a1-mum2 line produce few mutations. New mutants recovered from Zapalote chico are somatically stable.

Base Sequence↗
PubMed1998

In vitro elution of tobramycin and vancomycin polymethylmethacrylate beads and spacers from Simplex and Palacos.

In vitro studies of antibiotic elution from polymethylmethacrylate cement comparing Simplex (Howmedica, Rutherford, NJ) with Palacos brands (Richards, Memphis, TN) have shown variable results. This study compares the elution of tobramycin and vancomycin from Simplex and Palacos beads and spacers. Six-millimeter beads and spacers were incubated in phosphate-buffered saline, and the solution was sampled and changed daily until the concentration of antibiotic fell below the minimum inhibitory concentration (MIC) for Staphylococcus aureus. In all groups, the Palacos PMMA beads and spacers showed elution at higher levels and remained above the MIC longer than did the Simplex PMMA beads. Tobramycin had superior elution to vancomycin in all groups. This in vitro study shows that Palacos PMMA has superior elution properties to Simplex PMMA in tobramycin and vancomycin beads and spacers.

Anti-Bacterial Agents↗
PubMed1998

Relation of surface area to in vitro elution characteristics of vancomycin-impregnated polymethylmethacrylate spacers.

To study the relationship between surface area and antibiotic elution from antibiotic-impregnated polymethylmethacrylate (PMMA) spacers, a standard block spacer made of vancomycin (4 g) and 40 g of PMMA was compared with two unique spacer designs, the "donut" and "fenestrated." The spacers were incubated in phosphate-buffered saline, which was changed daily, and a microbiologic assay was used to measure the antibiotic activity of the eluates. The donut and fenestrated spacers had 12% and 40% more surface area than the standard spacer, respectively. There was no significant difference, however, in daily elution levels of antibiotic between the donut spacer and the standard spacer. The fenestrated spacer displayed significantly better elution than either the standard or donut spacers, with an average of 20% more antibiotic eluted on any given day.

Methylmethacrylates↗
PubMed1997

Fluconazole disc diffusion testing for the routine laboratory.

The increasing incidence of resistance to the antifungal agent, fluconazole, prompted the need for a rapid, reliable and easy-to-use susceptibility test. We have developed a disc diffusion test for fluconazole against Candida spp. suitable for a clinical laboratory. Disc diffusion tests on six different media were compared with MIC values. On the basis of correlation coefficient with MICs (r = -0.95), quality of growth and zone edge definition, Yeast Nitrogen Base agar with glucose (YNBG) produced the best results. Further studies on YNBG showed that the method is reliable for Candida albicans and for resistant isolates with no zone of inhibition, but results for the slower growing and uncommon species must be interpreted with some caution. Implementation of this test in the clinical laboratory has provided a much needed therapeutic service for clinicians within the hospital. It has also reduced the reliance on the reference laboratory for susceptibility results and the consequent costs involved.

Candida↗
PubMed1997

P3B and positive slow wave following real and dummy feedback on arithmetic rule-learning and perceptuomotor tasks.

Event-related Potentials (ERPs) were recorded to feedback during a cognitively demanding, arithmetic rule-learning task and a relatively simple, skill-oriented, perceptuomotor task. For both tasks, a compound feedback display was employed. It consisted of numeric feedback information presented simultaneously with a red or green light (50% each) which indicated whether the numeric information was real (valid) or dummy (invalid). The task and feedback-validity manipulations showed a functional dissociation between the P3b (350-450 msec.) and a Positive Slow Wave (600-900-msec.). P3b was larger for real than for dummy feedback; Positive Slow Wave was larger for rule-learning than for perceptuomotor tasks.

Adolescent↗
PubMed1995

Positive event-related potentials to real and dummy rule-learning feedback and to perceptuomotor feedback.

Amplitudes of 5 event-related potentials (ERPs) were recorded at 5 sites of 10 males to real (R-) and dummy (D-) feedback (FB) over two difficulty levels of a rule-learning task, with interspersed perceptuomotor (PM) task trials. Rule-learning R-FB for positive slow wave (PSW) and P3b was greater than for D-FB for both mean time-window and principal component factor score measures. FB effects varied by site for P2/P3a (mainly Fz-C4-Pz) and for a late PSW (LPSW; mainly C4-C3-Fz). A new ERP, P508, showed the greatest topographic differentiation, but no FB main effect. The following ERPs may reflect different sources: PSW versus P3b; P2/P3a versus LPSW; R-FB versus D-FB P2/P3a; R-FB versus D-FB LPSW; and P508 versus all others. LPSW was greater to simple than complex task difficulty; while the "P508" factor score trended towards being greater for complex than simple. ERP interpretation is in terms of stimulus recognition classification, comparative evaluation and development elaboration of mental models. Rule-learning D-FB exceeded PM accuracy R-FB for all ERPs but P2/P3a. Strongly implicated in these differences are preparatory acts in the former task as reflected by the PSW and LPSW.

Acoustic Stimulation↗
PubMed1991

Mutator activity in maize correlates with the presence and expression of the Mu transposable element Mu9.

Mutator is a powerful system for generating new mutants in maize. Mutator activity is attributable to a family of transposable, multicopy Mu elements, but none of the known elements is an autonomous (regulatory) element. This paper reports the discovery of Mu9, a 4942-base-pair Mu element that was cloned after it transposed into the Bronze-2 locus. Like other Mu elements, Mu9 has approximately 215-base-pair terminal inverted repeats and creates a 9-base-pair host sequence duplication upon insertion. A small gene family of elements that cross-hybridize to Mu9 has been found in all maize lines, and one of the other known Mu elements, Mu5, probably arose as a deletion of Mu9. Mu9 has several of the properties expected for the proposed regulator of Mutator activity. (i) The presence of Mu9 parallels the presence of Mutator activity in individuals from a line that genetically segregates for the Mu regulator. (ii) Lines that transmit Mutator to greater than 90% of their progeny have multiple copies of Mu9. (iii) Most maize lines that lack Mutator activity and that are not descended from Mutator lines lack the Mu9 element. (iv) Transcripts that hybridize to Mu9 are abundant in active Mutator lines, but they are absent from lines that have epigenetically lost Mutator activity. These correlations suggest that Mu9 is a candidate for the autonomous Mutator element.

Alleles↗
PubMed1984

Movement-related potentials during development: a replication and extension of relationships to age, motor control, mental status and IQ.

Three age groups of normals (children, preadolescents, and adults) and a group of mentally retarded adults performed a noncued button press task from which averaged movement-related potentials (MRPs) were derived. MRP wave shapes replicated our previously reported modal waveform types, except for the preadolescents, who showed no modal MRP. The normal groups showed a developmental shift in the prevalence of waveforms with the retarded differing from normal adults. The modal child waveform had a large amplitude positive-negative-positive form; the retarded had a uniphasic positive form; while normal adults showed the usual negative form. Major MRP types among children could not be attributed to differences in sampling or number of the trials averaged, or to trial-to-trial MRP variability. Background EEG activity did not differ in different modal MRP types. Modal child MRPs showed an initial peak positivity at Fz, and a late peak at Cz. The retarded had a sustaining central positivity developed by midepoch. MRP positivity and negativity were related to age, inhibition of extraneous eye movement (EM), and IQ. In children, greater cognitive proficiency is associated with adult-like MRP. The results suggest that positivity, in part, reflects a subject's efforts at inhibiting movement extraneous to the instructed task.

Adolescent↗
PubMed1981

In-vitro antigonococcal activity of rosoxacin (WIN 35213).

The in-vitro activity of rosoxacin against 173 isolates of Neisseria gonorrhoeae, including 17 beta-lactamase-producers, was tested by an agar dilution method. Of the isolates, 167 (including 16 of the beta-lactamase-producers) were inhibited by 0 . 06 mg/l of rosoxacin. The remaining six isolates, one of which produced beta-lactamase and the others were moderately resistant to penicillin, were inhibited by 0 . 12-0 25 mg/l of the compound. There was little correlation between the minimum inhibitory concentrations (MICs) of rosoxacin and penicillin, except for isolates with MICs of penicillin of 0 . 06-1 mg/l, for which correlation was good.

4-Quinolones↗
PubMed1976

Women among men: females in the male homosexual community.

The study uses empirical data to generate a preliminary theoretical analysis of the types of interaction and relationships that exist between male homosexuals on the one hand and lesbians and female heterosexuals on the other. Both males' and females' accounts of why they associate with one another in the male gay community are also examined. Methods appropriate to the description of interaction and the collection of accounts of behavior were used: participant observation and interviewing.

Adult↗