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Biomedical subjects

S M Colby

Publications and source records attributed to S M Colby.

At least 37 records · Page 2Linked to original sources
PubMed1998

Germacrene C synthase from Lycopersicon esculentum cv. VFNT cherry tomato: cDNA isolation, characterization, and bacterial expression of the multiple product sesquiterpene cyclase.

Germacrene C was found by GC-MS and NMR analysis to be the most abundant sesquiterpene in the leaf oil of Lycopersicon esculentum cv. VFNT Cherry, with lesser amounts of germacrene A, guaia-6,9-diene, germacrene B, beta-caryophyllene, alpha-humulene, and germacrene D. Soluble enzyme preparations from leaves catalyzed the divalent metal ion-dependent cyclization of [1-3H]farnesyl diphosphate to these same sesquiterpene olefins, as determined by radio-GC. To obtain a germacrene synthase cDNA, a set of degenerate primers was constructed based on conserved amino acid sequences of related terpenoid cyclases. With cDNA prepared from leaf epidermis-enriched mRNA, these primers amplified a 767-bp fragment that was used as a hybridization probe to screen the cDNA library. Thirty-one clones were evaluated for functional expression of terpenoid cyclase activity in Escherichia coli by using labeled geranyl, farnesyl, and geranylgeranyl diphosphates as substrates. Nine cDNA isolates expressed sesquiterpene synthase activity, and GC-MS analysis of the products identified germacrene C with smaller amounts of germacrene A, B, and D. None of the expressed proteins was active with geranylgeranyl diphosphate; however, one truncated protein converted geranyl diphosphate to the monoterpene limonene. The cDNA inserts specify a deduced polypeptide of 548 amino acids (Mr = 64,114), and sequence comparison with other plant sesquiterpene cyclases indicates that germacrene C synthase most closely resembles cotton delta-cadinene synthase (50% identity).

Alkyl and Aryl Transferases↗
PubMed1998

Brief motivational interviewing in a hospital setting for adolescent smoking: a preliminary study.

This study tested the feasibility and efficacy of a brief smoking intervention for adolescents in a hospital setting. Forty adolescent patients were randomized to receive either brief advice or a motivational interview, a nonconfrontational therapeutic intervention. Feasibility of brief smoking interventions with teen patients was supported by high rates of recruitment, retention, and quit attempts, and long periods of continuous abstinence. Although between-groups differences on smoking measures were not significant at 3-month follow-up, an effect size of h = .28 was noted. The sample showed significant decreases in smoking dependence and number of days smoked. Baseline stage of change, smoking rate, and depression were significant prospective predictors of smoking outcome. Implications for smoking intervention research with adolescents are discussed.

Adolescent↗
PubMed1998

Detection of alcohol use in adolescent patients in the emergency department.

OBJECTIVES: To examine 3 methods of detecting alcohol use among adolescent patients visiting a Level-1 regional trauma center. METHODS: Part 1 was a retrospective review of laboratory records and (13- to 19-year-old) patient medical records over the 1-year period from August 1993 to July 1994. Part 2 was a review of ICD-9 discharge diagnoses for the same age range during the same 1-year period. Part 3 involved prospective saliva alcohol testing of injured patients aged 13-17 years old. RESULTS: Part 1: A total of 522 blood tests were conducted and 160 (30.6%) were positive for alcohol. More than one-third of the alcohol-positive sample had alcohol ingestion as the only reason for their visits, i.e., they were uninjured. The alcohol-positive group was more likely to be male and older. Part 2: A total of 99 alcohol-related discharge diagnoses were given to adolescent patients. Alcohol abuse was the most common diagnosis. With the 2 methods of detection combined, 186 patients were identified. Part 3: A total of 119 saliva alcohol tests were conducted. One patient tested positive but had been identified while in triage as having used alcohol. CONCLUSION: In this study population, approximately one-third of adolescent patients tested for alcohol as part of routine clinical care were alcohol-positive but were not necessarily given an alcohol-related diagnosis. Thus, studies determining rates of alcohol-positive adolescents treated in EDs should use multiple methods of detection. Universal testing does not appear to be warranted for all injured adolescent patients.

Adolescent↗
PubMed1997

Effects of suppressing the urge to drink on the accessibility of alcohol outcome expectancies.

Previous work has shown that attempts to deliberately suppress a given thought is associated with heightened accessibility of thought-related information both during and following suppression (Wegner, 1994, Psychological Review, 101, 34-52). This study examined whether attempts to suppress the urge for alcohol would similarly be associated with heightened accessibility of alcohol-related information. Heavy social drinkers were exposed to the sight and smell of their usual alcoholic beverage either under the instructions to suppress their urge to drink alcohol or without such instruction. Following this task, participants were asked to make timed judgements about the applicability of a series of alcohol outcome expectancies. Results supported the view that suppression increases the accessibility of information in memory. Those in the Suppression condition were faster to endorse alcohol outcome expectancies following the exposure to alcohol cues than those in the Control condition. Findings are discussed in terms of cognitive strategies for regulating alcohol use and patterns of restrained drinking.

Adult↗
PubMed1997

Effects of alcohol cues on smoking urges and topography among alcoholic men.

Although the prevalence of smoking among alcoholics ranges up to 97%, little is known about mechanisms underlying the co-occurrence of smoking and alcohol use, or the role tobacco may play in alcohol treatment recovery. Adult male alcoholics in treatment (n = 30) were randomly assigned to visual and olfactory exposure either to alcohol cues or to control cues, and then were allowed to smoke while continuing visual exposure to the same cues. Exposure to alcohol cues resulted in significantly greater self-reported urge to drink and urge to smoke but had no significant effect on the topography of smoking behavior. When variance due to urge to smoke was controlled, greater urge to drink correlated negatively with number of cigarette puffs. The results provide some support for a priming hypothesis of tobacco's role on alcoholism recovery. Clinical and theoretical implications are discussed.

Adult↗
PubMed1995

High resolution matrix-assisted laser desorption/ionization time-of-flight analysis of single-stranded DNA of 27 to 68 nucleotides in length.

Mass spectra of single-stranded DNA oligonucleotides were acquired using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Resolution enhancement using space-velocity correlation focusing allows for facile observation of different oligomers, the direct observation of individual DNA-metal adducts, and investigation of counter ion structure.

Base Sequence↗
PubMed1995

Insertional inactivation of the Streptococcus mutans dexA (dextranase) gene results in altered adherence and dextran catabolism.

Streptococcus mutans is able to synthesize extracellular glucans from sucrose which contribute to adherence of these bacteria. Extracellular dextranase can partially degrade the glucans, and may therefore affect virulence of S. mutans. In order to isolate mutants unable to produce dextranase, a DNA library was constructed by inserting random Sau3AI-digested fragments of chromosomal DNA from S. mutans into the BamHI site of the streptococcal integration vector pVA891, which is able to replicate in Escherichia coli but does not possess a streptococcal origin of replication. The resultant plasmids were introduced into S. mutans LT11, allowing insertional inactivation through homologous recombination. Two transformants were identified which did not possess dextranase activity. Integration of a single copy of the plasmid into the chromosome of these transformants was confirmed by Southern hybridization analysis. Chromosomal DNA fragments flanking the plasmid were recovered using a marker rescue technique, and sequenced. Comparison with known sequences using the BLASTX program showed 56% homology at the amino acid level between the sequenced gene fragment and dextranase from Streptococcus sobrinus, strongly suggesting that the S. mutans dextranase gene (dexA) had been inactivated. The colony morphology of the dextranase mutants when grown on Todd-Hewitt agar containing sucrose was altered compared to the parent strain, with an apparent build-up of extracellular polymer. The mutants were also more adherent to a smooth surface than LT11 but there was no apparent difference in sucrose-dependent cell-cell aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Identification and genetic characterisation of melibiose-negative isolates of Streptococcus mutans.

Streptococcus mutans is frequently identified on the basis of phenotypic characteristics such as the ability to ferment carbohydrates. The usefulness of some of these identification tests may be limited in the case of isolates which are atypical with regard to their fermentation properties. We previously identified isolates of S. mutans which were unable to ferment melibiose, a characteristic which is included in some typing schemes. In all of these isolates there was a large chromosomal deletion which included the multiple sugar metabolism (msm) operon which encodes several genes involved in the uptake and metabolism of a number of sugars including melibiose. In the present study, sugar fermentation tests, ribotyping, colony hybridisation with DNA probes and polymerase chain reaction (PCR) were used to investigate the relatedness of these atypical isolates. The PCR and colony hybridisation procedures were based on amplification and detection of two genes: the wapA gene which encodes a surface protein found in all S. mutans strains and the gtfA gene which lies within the msm operon. The colony hybridisation and PCR results confirmed loss of the gtfA gene in the melibiose-negative isolates. Three new melibiose-negative isolates were also identified, but in only 2 of these was the gtfA gene absent, the third did not appear to have lost this region of the chromosome. Biotyping, as well as ribotyping based on an EcoRI digest of chromosomal DNA, revealed that the melibiose-negative isolates fell into a number of distinct groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Outer Membrane Proteins↗
PubMed1995

Interrelationship of smoking and alcohol dependence, use and urges to use.

OBJECTIVE: The relationship between tobacco dependence and alcohol dependence has received little empirical scrutiny. The present study of alcoholics in treatment for alcoholism investigated pretreatment tobacco and alcohol history and dependence, as well as subjective responsivity to alcohol cues. METHOD: Eighty-three male alcoholics underwent a questionnaire assessment of smoking and drinking pretreatment followed by a laboratory assessment of reactivity to alcohol cues. RESULTS: The analyses demonstrate that (1) pretreatment tobacco dependence and pretreatment alcohol dependence are related, (2) alcohol dependence predicts urges to smoke during alcohol treatment, (3) exposure to alcohol cues results in increased urge to smoke, (4) smoking when ill predicts urge to drink during alcohol cue exposure and (5) urge to smoke is positively correlated with urge to drink. CONCLUSIONS: These data, collected in a population of alcoholics not currently receiving smoking interventions, indicate that smoking may be a factor to address during alcohol treatment. The clinical importance of these data is discussed.

Adolescent↗
PubMed1994

Cue reactivity as a predictor of drinking among male alcoholics.

Social learning theories suggest that conditioned responses may increase the risk for relapse. Responses to alcohol use cues (cue reactivity) are associated with variables suggestive of risk but little research exists on the relationship of cue reactivity to treatment outcome. Alcoholic men admitted for detoxification to a treatment program (n = 45) underwent a cue reactivity assessment protocol, and 91% received 3-month follow-up interviews. Greater salivary reactivity predicted greater frequency of drinking during follow-up. Attentional factors added independent variance to the prediction of drinking outcome, with greater attention to stimulus or to response predicting less drinking. Cue reactivity did not predict length of hospital stay or latency to first drink. Results are discussed in the context of information processing, social learning theories, and clinical implications for relapse prevention.

Adult↗
PubMed1994

Alcohol cue reactivity and mood induction in male and female alcoholics.

The purpose of this study was twofold: to investigate gender differences in alcohol cue reactivity, and to study the effect of individualized mood induction on cue reactivity. Male (n = 38) and female (n = 19) alcoholics were exposed to an alcoholic beverage before and after mood induction to assess their reactivity to the beverage cues. The mood induction was based on a situation the subject had identified as being high risk for relapse. Subjects showed urge and salivary reactivity in response to alcohol beverage cues prior to mood induction, and the induction of mood enhanced urge reactivity in both men and women. Analyses with alcohol urge reactors (subjects that demonstrate an increased urge to drink alcohol in response to an alcoholic beverage cue) suggested that women show more urge reactivity in response to negative moods than do men. No gender differences were seen in reactivity to beverage cues alone. These results identify an important gender difference in the effect of negative moods on cue reactivity and suggest that negative mood situations may place women at a higher risk for relapse than men.

Adolescent↗
PubMed1994

The effects of cue exposure on reaction time in male alcoholics.

The present study investigates reaction time (RT) as a measure of attentional deficits produced during alcohol cue exposure. Twenty-four male alcoholic patients responded to a series of computer-generated tones as rapidly as possible during baseline and again during either an alcohol cue exposure period or exposure to a control beverage (water). Patients required increased time to respond to the tones when exposed to alcohol cues. No such increase in RT was found during exposure to a control beverage. In addition, RT was significantly correlated with self-reported urge to drink. These data provide initial validation for the use of RT as an objective measure of cue reactivity. Both theoretical and clinical implications for the use of RT as a measure of the effects of cue exposure are discussed.

Adolescent↗
PubMed1993

4S-limonene synthase from the oil glands of spearmint (Mentha spicata). cDNA isolation, characterization, and bacterial expression of the catalytically active monoterpene cyclase.

The committed step in the biosynthesis of monoterpenes in mint (Mentha) species is the cyclization of geranyl pyrophosphate to the olefin (-)-4S-limonene catalyzed by limonene synthase (cyclase). Internal amino acid sequences of the purified enzyme from spearmint oil glands were utilized to design three distinct oligonucleotide probes. These probes were subsequently employed to screen a spearmint leaf cDNA library, and four clones were isolated. Three of these cDNA isolates were full-length and were functionally expressed in Escherichia coli, yielding a peptide that is immunologically recognized by polyclonal antibodies raised against the purified limonene synthase from spearmint and that is catalytically active in generating from geranyl pyrophosphate a product distribution identical to that of the native enzyme (principally limonene with small amounts of the coproducts alpha- and beta-pinene and myrcene). The longest open reading frame is 1800 nucleotides and the deduced amino acid sequence contains a putative plastidial transit peptide of approximately 90 amino acids and a mature protein of about 510 residues corresponding to the native enzyme. Several nucleotide differences in the 5'-untranslated region of all three full-length clones suggest the presence of several limonene synthase genes and/or alleles in the allotetraploid spearmint genome. Sequence comparisons with a sesquiterpene cyclase, epi-aristolochene synthase from tobacco, and a diterpene cyclase, casbene synthase from castor bean, demonstrated a significant degree of similarity between these three terpenoid cyclase types, the first three examples of this large family of catalysts to be described from higher plants.

Amino Acid Sequence↗
PubMed1993

Cue exposure with coping skills treatment for male alcoholics: a preliminary investigation.

Although early investigations were promising, no controlled follow-up studies have investigated the effectiveness of cue exposure treatment for alcoholics. In this study, inpatient alcoholics received either cue exposure integrated with urge coping skills training (CET, n = 22) or a contrast condition (CC) involving daily contact with assessment only (n = 18) in addition to standard treatment. Comprehensive assessment measures were used to investigate change in process and outcome variables. In the second 3 months after treatment, the CET group included more patients who were completely abstinent, had a higher percentage of abstinent days, and tended to report fewer drinks per day than did patients in the contrast condition. The significantly greater use of coping skills during follow-up by the CET group and the significant relationship of these coping skills to decreased drinking suggest that treatment effects were due, at least in part, to the coping skills training, consistent with recent formulations. Theoretical and treatment implications are discussed.

Adaptation, Psychological↗
PubMed1993

Alcohol cue reactivity: effects of detoxification and extended exposure.

Alcoholics' reactions to drinking-related stimuli (cue reactivity) have been well documented and alcohol cue exposure treatment has been conducted recently in several clinical trials. Prior to conducting large-scale clinical trials it is important to know what effects detoxification may have on cue reactivity. However, no information is available about the effects of stage of detoxification or of detoxification medication on alcohol cue reactivity. In this study, 45 male alcoholics, detoxified without medication, were assessed during either their second, fourth or sixth day of withdrawal. Further, their reactivity was compared to that of alcoholics detoxified with chlordiazepoxide (n = 15), and to that of alcoholics in their fourth week after drinking (n = 28). Cue reactivity assessment investigated salivation and urge to drink after 3 minutes of water cue exposure and then after 3 minutes of alcohol cue exposure. Urges to drink were assessed during an additional 15 minutes of alcohol exposure to explore latency to maximum reactivity and habituation. Reactivity did not differ as a function of group membership, although salivation was elevated to both beverages during the first week of detoxification. Of the sample, 70% reacted to alcohol with increased urge and 65% with increased salivation, with no difference between groups in proportions of reactors. The maximum urge to drink occurred in the first 6 minutes of alcohol exposure, followed by a gradual and significant decrease. There were no differences on these measures between alcoholics in their first or fourth week after their last drink. Implications for theory and clinical applications are discussed.

Adaptation, Psychological↗