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Biomedical subjects

K A Barton

Publications and source records attributed to K A Barton.

13 recordsLinked to original sources
PubMed2001

The failure of intensive self-regulatory treatment with chronic daily headache: a prospective study.

Sixteen patients with chronic daily headache (HA) of moderate to severe intensity received 20 sessions of self-regulatory treatment including progressive muscle relaxation, thermal biofeedback, and cognitive stress coping therapy. Four stopped treatment after 12 visits (but had received all 3 treatment components). Only 2 of 12 completers (17%) showed more than 50% reduction in HA Index based on daily diaries. Chronic daily HA continues to be relatively refractory to self-regulatory treatment.

Adult↗
PubMed2000

Psychometric properties of a measure of aggressive driving: the Larson Driver's Stress Profile.

This paper presents three studies on Larson's 1996 Driver's Stress Profile, a measure of aggressive driving tendencies. In Study 1, utilizing 33 individuals (15 men, 18 women) who took the test twice with one week between tests, we found the test to have good test-retest reliability (r = .93). In Study 2, utilizing 176 individuals (77 men, 99 women), we found different preliminary norms for men and women and good internal consistency (.93). We also found significant correlation between the total test scores and age (r = -.27) and a significant correlation (age corrected) between total test scores and number of self-reported MVAs (r = .28). An exploratory factor analysis indicated that three factors, including 28 of the 40 items, accounted for 43.4% of the variance. In study 3, utilizing the same subjects as in Study 2 (84 individuals from the community of average age 35.3 yr.; 92 college students of average age 18.9 yr.), we found the full scale scores correlated significantly with scores on Trait Anger and Anger Out and Type A Behavior, especially speed and impatience. Finally, scores correlated significantly with the Deffenbacher Driving Anger Scale (r = .57) but clearly tapped processes different, in part, from those measured by the Deffenbacher, et al. scale (1994). Overall, the Driver's Stress Profile appears to be a sound, reliable, and valid scale for use with aggressive driving.

Adolescent↗
PubMed1997

Surgical results in malignant glaucoma refractory to medical or laser therapy.

We investigated the surgical results in 25 patients identified with malignant (ciliary block) glaucoma. Four of these patients (16%) had successful outcomes following laser treatment alone. Nineteen patients (76%) underwent microsurgery for glaucoma refractory to conventional medical and/or laser therapy and are the subjects of this study. Core vitrectomy was successful in 4 of 6 pseudophakic patients (67%) and in 1 of 4 phakic patients (25%). Combined cataract extraction and vitrectomy had a higher success rate in patients undergoing posterior capsulectomy at the time of surgery (5 of 6 patients; 83%) compared with those patients left with an intact posterior capsular bag (1 of 4 patients; 25%). Intracapsular cataract extraction was successful in 1 of 2 patients (50%). We conclude that surgical vitrectomy in the presence of an intact posterior capsule may preclude the surgical resolution of aqueous misdirection. In eyes with pre-existing cataract, we recommend combined lens extraction, primary posterior capsulectomy and surgical vitrectomy for the surgical management of phakic malignant glaucoma.

Adult↗
PubMed1996

Antecedents and consequences of acute stress disorder among motor vehicle accident victims.

The aim of this study was to examine differences between motor vehicle accident (MVA) victims diagnosed retrospectively with Acute Stress Disorder (ASD) and subsequent Post-Traumatic Stress Disorder (PTSD), and MVA victims with only PTSD. A total of 14 ASD subjects and 28 PTSD subjects (matched on age and on sex) were compared on subjects' levels of functioning and symptom severity at three time-points: pre-MVA, 1-4 months post-MVA (initial assessment), and 6 months post initial assessment. Fourteen non-MVA subjects were included as controls in the analyses for pre-MVA differences and presence of psychopathology at time of initial assessment. ASDs had higher rates of previous mood disorders (other than major depression), previous AXIS-I disorders, and previous AXIS-II disorders than did PTSDs. No differences existed between the groups at 6-month follow-up. These results provide clinically useful information regarding characteristics that predispose people to develop ASD in the aftermath of a trauma. Previous research with trauma victims has demonstrated dissociative symptoms to be associated with higher PTSD symptom severity and longer symptom duration, but our follow-up results suggest that ASD, which is characterized by dissociative symptomatology, is not indicative of poorer outcome in MVA victims.

Accidents, Traffic↗
PubMed1996

One-year prospective follow-up of motor vehicle accident victims.

One-hundred and thirty-two victims of motor vehicle accidents (MVAs), who sought medical attention as a result of the MVA, were assessed at three points in time: 1-4 months post-MVA, 6 months later, and 12 months later. Of the 48 who met the full criteria for Post-Traumatic Stress Disorder (PTSD) initially, half had remitted at least in part by the 6-month follow-up point and two-thirds had remitted by the 1-yr follow-up. Using logistic regression, 3 variables combined to correctly identify 79% of remitters and non-remitters at the 12-month follow-up point: initial scores on the irritability and foreshortened future symptoms of PTSD and the initial degree of vulnerability the subject felt in a motor vehicle after the MVA. Four variables combined to predict 64% of the variance in the degree of post-traumatic stress symptoms at 12 months: presence of alcohol abuse and/or an Axis-II disorder at the time of the initial assessment as well as the total scores on the hyperarousal and on avoidance symptoms of PTSD present at the initial post-MVA assessment.

Accidents, Traffic↗
PubMed1989

Cytokinin antagonist activity of substituted phenethylamines in plant cell culture.

A series of structurally related substituted phenethylamines shows extreme toxicity toward wild-type callus tissue cultures of tobacco (Nicotiana tabacum), soybean (Glycine max), corn (Zea mays), and sunflower (Helianthus annuus L.), but tobacco crown gall cultures are resistant to the compounds. The essential components that result in toxicity of the phenethylamines include one aromatic hydroxyl and one primary aliphatic amino group. A series of attenuated crown gall cultures, generated by transformation of tobacco with various modified Agrobacterium strains, has been used to demonstrate that the resistance of crown galls to the phenethylamines is due to the expression in these tissues of isopentenyl transferase, a first step in cytokinin biosynthesis. The toxicity of the compounds to tissue cultures is very rapid, but can be overcome by prior exposure of the calli to exogenous cytokinin. Because of the relationships we have observed between cytokinins and these compounds, we propose that the substituted phenethylamines may represent a class of chemicals that can be used as specific probes to further an understanding of cytokinin metabolism in plant tissues.

Journal Article↗
PubMed1987

Bacillus thuringiensis section sign-Endotoxin Expressed in Transgenic Nicotiana tabacum Provides Resistance to Lepidopteran Insects.

The crystal proteins, or section sign-endotoxins, of Bacillus thuringiensis are specifically lethal to Lepidopteran insects. We utilized a truncated and modified portion of a cloned crystal protein gene to construct a chimeric gene capable of expression in plant cells. Using an Agrobacterium tumefaciens binary vector system, we then transferred the chimeric toxin gene into tobacco (Nicotiana tabacum cv Havana 425) cells and regenerated recombinant plants. One to several copies per cell of the toxin gene are routinely present in the recombinant plants. Hybridization experiments demonstrated that these plants had a new RNA species of the size expected for the truncated toxin mRNA, and a polypeptide having the mobility expected for the truncated toxin was detected by immunoblotting. Significant variation was found in the levels of toxin-specific RNA expression between different recombinants, but the levels of hybridizing RNA in transformants correlated with the level of toxicity demonstrated against Manduca sexta (tobacco hornworm), and other Lepidopteran insects. The recombinant genes were transmitted to progeny and resistance to insects was maintained, thus demonstrating that the introduction of toxin genes into plants may be a practical method of providing protection against certain insect pests.

Journal Article↗
PubMed1983

Prospects in plant genetic engineering.

The functional expression of a novel gene in a genetically engineered plant has not yet been reported. One major barrier in movement toward this goal is our limited understanding of the molecular bases of gene expression. Attempts to establish genetic engineering as a practical facet of plant breeding are also complicated by the fact that genes for most important plant characteristics have not yet been identified. However, the benefits to be gained from all aspects of plant improvement are stimulating research into both the development of plant transformation technology and the isolation and characterization of genes responsible for valuable traits. As scientists develop greater knowledge of plant molecular genetics, we can expect to see practical applications in such diverse areas as improvement of plant nutritional quality, decreases in fertilization requirements, and increases in resistance to environmental stresses and pathogens.

Agriculture↗
PubMed1983

Regeneration of intact tobacco plants containing full length copies of genetically engineered T-DNA, and transmission of T-DNA to R1 progeny.

Cloned DNA sequences encoding yeast alcohol dehydrogenase and a bacterial neomycin phosphotransferase have been inserted into the T-DNA of Agrobacterium tumefaciens plasmid pTiT37 at the "rooty" locus. Transformation of tobacco stem segments with the engineered bacterial strains produced attenuated crown gall tumors that were capable of regeneration into intact, normal tobacco plants. The yeast gene and entire transferred DNA (T-DNA) were present in the regenerated plants in multiple copies, and nopaline was found in all tissues. The plants were fertile, and seedlings resulting from self-pollination also contained intact and multiple copies of the engineered T-DNA. Expression of nopaline in the germinated seedlings derived from one regenerated plant was variable and did not correlate with the levels of T-DNA present in the seedlings. Preliminary evidence indicates that nopaline in progeny of other similarly engineered plants is more uniform. The disarming of pTiT37 by insertions at the "rooty" locus thus appears to produce a useful gene vector for higher plants.

Alcohol Oxidoreductases↗
PubMed1982

The biosynthesis and processing of high molecular weight precursors of soybean glycinin subunits.

The predominant storage protein of soybean seed, glycinin, is composed of two heterogeneous classes of related subunits, the acidics (Mr approximately 38,000) and the basics (Mr approximately 22,000). Immunoreaction of polypeptides translated in vitro from isolated seed mRNA using antibodies prepared against either purified acidic or basic subunit groups precipitated precursor polypeptides of Mr = 60,000 to Mr = 63,000. High pressure liquid chromatography fingerprinting of trypsin-generated fragments from in vitro synthesized precursors showed fragments specific to both acidic and basic subunits. No mature acidic or basic subunits were detected in vitro translation reactions by either immunoprecipitation or high pressure liquid chromatography fingerprinting. Pulse-labeling of cotyledons growing in culture with [3H]glycine showed rapid accumulation of label in glycinin precursors of Mr = 59,000 to Mr = 62,000. Although in vivo synthesized precursors had slightly greater electrophoretic mobility than in vitro synthesized precursors, little label initially appeared in mature glycinin subunits. After several hours of continued cotyledon growth in absence of label, precursors were processed and label accumulated in both acidic and basic subunit groups. Recombinant plasmids were prepared by reverse transcription of soybean seed mRNA, and clones which encode glycinin precursors were identified by heteroduplex-hybridization of translatable messages. Northern blot analysis of seed mRNA shows the mRNA-encoding glycinin precursors to migrate at Mr = 0.71 X 10(6) on agarose gels, corresponding to approximately 2050 nucleotides. This is sufficiently large to encode a polypeptide consisting of both a glycinin acidic and basic subunit.

Chromatography, High Pressure Liquid↗
PubMed1981

Biosynthesis of subunits of the soybean 7S storage protein.

Biosynthesis of the alpha', alpha, and beta subunits of the soybean 7S storage protein (conglycinin) was studied by in vivo and in vitro experiments. One hour in vivo labeling produced polypeptides of 72 kilodaltons (kD) and 78 kD which, in a subsequent 1-h chase period, gave rise to a heterodisperse band of polypeptides of 76-83 kD, the apparent molecular weights of mature alpha and alpha', respectively. After a 3-h chase period only mature alpha and alpha' were labeled. The pre-alpha' (80 kD) and pre-alpha (78 kD) polypeptides produced by in vitro translation of total seed poly(A)+ RNA did not coelectrophorese with polypeptides labeled in vivo. The mature beta-subunit (53 kD), produced in vivo during the 1-h chase period, apparently was translated as a 50 kD polypeptide in vitro. The data suggest that, in vivo, primary translation products undergo both cotranslational and posttranslational modifications during the formation of mature subunits. cDNA clones complementary to soybean seed poly(A)+ RNA were prepared and subsequently identified by hybrid-release and immunoprecipitation experiments. Clone pGmc 236 (550 base pairs) (bp) was shown to contain sequences complementary to mRNAs for the alpha', alpha, and beta subunits on the basis of hybrid-release experiments, corroborating tryptic fingerprints that demonstrate that these subunits are closely related to each other. Although selected by a single cDNA clone, the mRNAs are not identical because the alpha' mRNA was eluted from the filter-bound cDNAs at a lower temperature than were the alpha beta mRNAs, pGmc 236 hybridized on Northern blots to mRNAs of approximately 2500 nucleotides, sufficient size to code for the alpha' or alpha subunit of the 7S storage protein.

Antigens, Plant↗