Search PubMed⌕ Search

Biomedical subjects

G C Davis

Publications and source records attributed to G C Davis.

At least 55 records · Page 3Linked to original sources
PubMed1987

Posttraumatic stress disorder. The stressor criterion.

Posttraumatic stress disorder (PTSD) was officially introduced into psychiatric nomenclature in 1980, when it was incorporated into DSM-III. There is as yet little empirical research on the validity of the diagnosis. Literature on disasters, civilian and wartime, and on more ordinary stressful life events does not support the view that extreme stressors form a discrete class of stressors in terms of the probability of psychiatric sequelae or the distinctive nature of subsequent psychopathology. Extraordinary stressors are like more ordinary stressful events with respect to their complex differential effects upon individuals. Personal characteristics and the nature of the social environment modify the likelihood and form of the response of individuals to all types of stressors.

Humans↗
PubMed1987

Posttraumatic stress disorder: the etiologic specificity of wartime stressors.

The authors examined the effects of wartime stressors in a sample of 69 Vietnam veterans who were psychiatric inpatients in a Veterans Administration hospital. Participation in atrocities and the cumulative exposure to combat stressors, each independently of the other, conferred a significant risk for posttraumatic stress disorder. In contrast, the effect of these war experiences on the onset of panic, major depression, and mania was not significant. The results indicate that extreme stressors are uniquely linked with posttraumatic stress disorder's characteristic cluster of symptoms but challenge DSM-III's implicit assumption that the reexperienced trauma is the stressor responsible for posttraumatic stress disorder.

Adult↗
PubMed1986

Evaluation of immunosorbents for the analysis of small molecules. Isolation and purification of cytokinins.

This paper describes the preparation and evaluation of immunosorbents for the isolation of cytokinins. The nature of both the solid support and the linkage chemistry affected the non-specific adsorption of sample contaminants and the characteristics of the immobilized antibody. All the immunosorbents investigated provided sufficient purification of cytokinins for high-performance liquid chromatographic analysis with no further clean-up. This demonstrates a rapid and powerful purification method for small molecules for which antibodies can be generated. As a consequence, the procedures described for the immobilization of cytokinin antibodies are generally applicable to the preparation of immunosorbents.

Animals↗
PubMed1986

An improved enzymatic synthesis of labeled gibberellin A12-aldehyde and gibberellin A12.

The biochemical synthesis of labeled gibberellin A12-7-aldehyde (GA12ald) and and gibberellin A12 (GA12) from labeled R,S-mevalonic acid (MVA) using cell-free extracts from pumpkin (Cucurbita maxima) endosperm has been improved over the previously reported procedure. Three major improvements were developing a one-step HPLC procedure to isolate GA12ald and GA12 in radiochemically pure form; adjusting the pH of the reaction mix to pH 6.9 which increased the GA12ald/GA12 ratio over that at pH 7.8 by ca. 18-fold while reducing the combined yield of these two compounds by less than 17%; and developing a technique that permitted sampling of the fruits without interrupting growth; this doubled the fraction of extracts with "high activity." Conversion of MVA into GA12ald or GA12 displayed Michaelis-Menten kinetics with half-maximal synthesis at 0.4 mM MVA. Four-hour incubations afforded the highest yields from 0.25 mM MVA. Up to 15 and 7% of the MVA was incorporated into GA12ald and GA12, respectively. About one-quarter of the extracts incorporated at least 10% of the 0.25 mM MVA into GA12ald. One pumpkin fruit can provide sufficient endosperm to synthesize ca. 0.6 mumol of GA12ald.

Cell-Free System↗
PubMed1986

Chronic stress and major depression.

Six-month and lifetime rates of DSM-III major depressive disorder (MDD) and characteristics of the disorder were compared in mothers of children with disabilities (chronic stress sample, n = 310) and in a geographically based probability sample (controls, n = 357). The presence of DSM-III MDD was ascertained by the National Institute of Mental Health Diagnostic Interview Schedule. Although mothers in the chronic stress sample had significantly more depressive symptoms, rates of MDD were not significantly different in the two samples. The women with MDD in the chronic stress sample reported a lower age of onset and more episodes in lifetime than diagnostically comparable controls, but the two samples did not differ in symptomatology of worst episode. The data do not support an etiologic role for chronic stress in MDD, nor do they support the hypothesis that chronic stress is associated with a unique symptom profile or more severe episodes. They suggest a role for chronic stress in precipitating episodes, although the evidence on this point must be interpreted with caution.

Adult↗
PubMed1986

Abnormalities of fine motor control in schizophrenia.

Response time and fine motor control during a classification task were examined in schizophrenics and nonschizophrenics. The task involved decisions about either the sensory characteristics of auditory and visual stimuli or the referential meanings of spoken words and viewed pictures. Nonschizophrenics responded more quickly and exhibited a smoother and faster motor response on all tasks. Response time and motor control were influenced by stimulus modality and the complexity of the classification task in both groups. In the analysis of motor control, the schizophrenics differed from the nonschizophrenics in exhibiting a pattern suggestive of a specific difficulty with decisions involving referential meaning. The observed motor control dysfunction in schizophrenics is a psychomotor deficit similar to previously reported abnormalities in smooth pursuit eye movement. Further, the interaction of group and task variables in the motor response suggests that decisions about the abstract referential meaning of words and pictures produce greater cognitive loads in schizophrenics than in nonschizophrenics.

Adult↗
PubMed1986

Descriptive, biological, and theoretical aspects of borderline personality disorder.

Although the diagnosis of borderline personality disorder has reasonable interrater and test-retest reliability, its discriminative validity is poor. The authors review studies indicating that the patient group subsumed by the borderline category actually includes those with various affective, organic, and schizotypal disorders. They speculate that borderline personality disorder represents a broad range of affective disorders resulting in part from childhood object loss, which may impair the reinforcement mechanisms necessary for the development of competent object relations.

Animals↗
PubMed1986

Reliability of Andreasen's thought, language and communications disorder scale.

The study of disordered thinking has been hampered by a lack of clinical instruments aimed at the measurement of thought disorder. Andreasen has proposed a rating scale for thought disorder (TLC) and reported on its reliability and preliminary aspects of its validity. In our study, a psychiatrist and physician assistant rated 98 psychiatric inpatients using the TLC and BPRS. Interrater reliability ranged from 0.35 to 0.80 (weighted kappa) on 18 aspects of thought disorder and one global item. The order of reliability for the 18 individual items was strongly correlated between the Andreasen sample and our own (r = 0.77). While the BPRS thought disorder scale was significantly related to the global rating of thought disorder on the TLC (r = 0.71), only half of the variance in thought disorder measured by the TLC was accounted for by the BPRS factor. Thus, this study supports Andreasen's contention that the TLC is a reliable instrument and suggests that the instrument may provide additional information about thinking disorders.

Communication↗
PubMed1985

Refining DSM-III criteria in Major Depression. An assessment of the descriptive validity of criterion symptoms.

In this study we estimate the power of DSM-III Major Depression (MDD) symptoms to discriminate MDD from (1) Generalized Anxiety Disorder (GAD) and (2) no disorder. The NIMH-DIS was administered to 319 women exposed to chronic stress (all were mothers of disabled children). Two methods were used: (1) conditional probabilities, and (2) multiple regression analysis. Symptoms had greater utility in discriminating MDD from no disorder than from GAD. 'Gained weight' and 'thinking about death' had the least efficacy in either discrimination. 'Hypersomnia' and 'insomnia' contributed to the discrimination from no disorder, whereas 'fatigue' and 'sex disinterest' discriminated MDD from GAD. 'Guilt', 'trouble concentrating', 'lost appetite' and 'wanted to die' were important in both comparisons. Despite recent emphasis on observable behaviors and physiologic measures, guilt, a subjectively experienced inner state, was the most important symptom in MDD.

Anxiety Disorders↗
PubMed1985

Measuring thought disorder with clinical rating scales in schizophrenic and nonschizophrenic patients.

The distinction between disorders of thought structure and disorders of thought content in a diagnostically heterogeneous psychiatric population was empirically tested using factor analysis applied to the item scores on two common clinical rating scales, the Brief Psychiatric Rating Scale and Andreasen's Thought, Language, and Communication Scale. The factor structure supported the separation of disordered thinking into disorders of thought content and disorders of thought structure or communication. Additionally, our results indicate that both aspects of disordered thinking are present in schizophrenic and manic patients; neither is specifically characteristic of schizophrenia. Indeed, disordered thought structure appears to be more common or worse in the manic patient than in the schizophrenic patient.

Bipolar Disorder↗
PubMed1985

DSM-III generalized anxiety disorder: an empirical investigation of more stringent criteria.

The diagnoses of generalized anxiety disorder (GAD) according to DSM-III and according to revised criteria (requiring 6 months' duration and 6 symptoms) were determined by the use of the National Institute of Mental Health Diagnostic Interview Schedule in a probability sample of 357 women. The DSM-III GAD lifetime rate of 45% was reduced by a factor of five when the revised definition was applied. The reduction was due chiefly to the longer duration criterion. Requiring a higher number of symptoms did not raise the threshold for the diagnosis, since 74% of persons with a period of 1 month or more of generalized anxiety reported six symptoms. Although chronicity was associated with more pervasive symptomatology, the excess in symptoms appears to be due to the very high prevalence of major depression (73%) among the newly defined (i.e., chronic) GAD positives.

Adult↗
PubMed1985

The nosologic status of borderline personality: clinical and polysomnographic study.

The REM latencies of 24 nonschizotypal borderline outpatients--who were not in the midst of a major depressive episode--were in the range of those of 30 patients with primary major depression but were significantly shorter than those of 16 patients with nonborderline personality disorders and 14 nonpsychiatric controls. Also, more of the borderline subjects had lifetime diagnoses of affective disorder, such as dysthymic, cyclothymic, and bipolar II disorder, and of a spectrum of anxiety and somatization disorders. The authors conclude that contemporary operational criteria for borderline disorder identify a wide net of temperamental disorders with strong affective coloring rather than a unitary nosologic entity.

Adult↗
PubMed1985

Borderline: an adjective in search of a noun.

Outpatients diagnosed as borderline (N = 100) were prospectively followed for 6-36 months and examined from phenomenologic developmental, and family history perspectives. At index evaluation, 66 met criteria for recurrent depressive, dysthymic, cyclothymic, or bipolar II disorders, and 16 for those of schizotypal personality. Other subgroups included sociopathic, somatization, panic-agoraphobic, attention deficit, epileptic, and identify disorders. Compared with nonborderline personality controls, borderlines had a significantly elevated risk for major affective but not for schizophrenic breakdowns during follow-up. Prominent substance abuse history, tempestuous biographies, and unstable early home environment were common to all diagnostic subgroups. In family history, borderlines were most like bipolar controls, and differed significantly from schizophrenic, unipolar, and personality controls. It is concluded that, despite considerable overlap with subaffective disorders, the current adjectival use of this rubric does not identify a specific psychopathologic syndrome.

Adolescent↗
PubMed1985

Combat-related flashbacks in posttraumatic stress disorder: phenomenology and similarity to panic attacks.

Combat veterans (N = 25) with posttraumatic stress disorder had flashbacks related to their combat stressors, which included major losses and exposure to danger. Certain affects, loud noises, fatigue, and personal stress tended to precipitate flashback episodes. Flashbacks began a year or more after exposure to combat in 50% of patients; 56% of patients experienced daily flashbacks. Flashback phenomenology met DSM-III criteria for panic attacks. The similarity of flashbacks to panic attacks suggests treatment trials with monoamine oxidase inhibitors or imipramine for these selected symptoms.

Adult↗