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Biomedical subjects

D R Evans

Publications and source records attributed to D R Evans.

At least 127 records · Page 7Linked to original sources
PubMed1977

Modification and factorial analysis of the Leyton Obsessional Inventory.

The Leyton Obsessional Inventory was modified into a paper-and-pencil form to facilitate its group administration. Factor analysis was carried out on the modified version replies of 173 college students. The factors obtained were compared to those extracted by Cooper and Kelleher (1973) for the original inventory. Similarities and differences in factors were attributed to cultural factors and differences in the sample populations. The treatment implication of obtaining multiple symptom factors in future studies with obsessional patients was stressed.

Activities of Daily Living↗
PubMed1977

Development of a state measure of obsessive compulsive behavior.

The Reaction Inventory-Interference was developed to identify obsessional thoughts and compulsive acts, which interfere with an individual's daily activities. The 50 items in the inventory were administered to 172 Ss. On the basis of item test correlations, 40 items were retained for subsequent analyses. The estimate of internal consistency for the 40 item inventory was .95. The correlation between the 40-item inventory and the "symptom" score on the Leyton Obsessional Inventory was .66. Factor analysis of the 40-item inventory yielded nine factors.

Compulsive Behavior↗
PubMed1977

Use of the MMPI to predict effective hotline workers.

The present study investigated the use of the MMPI to discriminate between two groups of hotline volunteers: those who after training would become effective interviewers and those who would not. Effective interviewers were defined as those who emitted 40% or more good responses when they were responding to a crisis call. The criterion measure employed was the Therapist Error Checklist. When a specification equation based on standard MMPI scales was used, 91% of effective interviewers and 90% of ineffective interviewers were identified correctly.

Counseling↗
PubMed1976

Agammaglobulinemia in a horse with evidence of functional T lymphocytes.

Agammaglobulinemia was diagnosed in a 1-year-old Thoroughbred horse on the basis of the following observations: (1) absence of serum immunoglobulins M, A, and G(T); (2) small amounts of serum immunoglobulin G (16 mg/100 ml); (3) absence of specific antibody in the serum of the horse following immunization and challenge exposure to 2 antigens; (4) absence of plasma cells, primary follicles, and germinal centers in a lymph node removed after antigenic stimulation; (5) absence of "natural" serum antibodies to rabbit-erythrocytes which were easily detectable in age-matched control horse serums; and (6) increased susceptibility to infections. There was evidence of functional cell-mediated immunity which included a skin response to injected phytolectins, skin response to antigen challenge following sensitization, and in vitro proliferative response of lymph node cells to phytohemagglutinin. An intact cell-mediated immune response was also supported by the observation that the horse lived to 17 months of age without antibody production, whereas horses with an absence of both antibody production and cell-mediated immunity (combined immunodeficiency) die by 4 months of age without immunologic intervention. The known features of agammaglobulinemia in this horse are similar to those in sex-linked agammaglobulinemia in persons and are unique among the immunodeficiences described in other animals.

Agammaglobulinemia↗
PubMed1975

Attitudes and smoking habits of Australian doctors.

In a national survey of 1,276 Australian doctors, information was obtained about their present smoking havits, any changes in their smoking habits, their opinions of the health risks associated with smoking, and the advice they gave to their patients about smoking. The results indicated that only 14% of doctors currently smoked cigarettes, and that, of all the doctors who were now ex-smokers, 72% had given up smoking more than five years before-most of them for health reasons. Most exressed a strong belief that smoking and ill health were associated and 63% encouraged their patients to give up smoking whenever possible.

Adult↗
PubMed1975

Isolation and properties of a species produced by the partial dissociation of aspartate transcarbamylase from Escherichia coli.

A species produced by the reaction of aspartate transcarbamylase (C6R6) with 6 to 12 eq of p-hydroxymercuribenzoate was isolated by DEAE-Sephadex chromatography. Purified material was completely dissociated with mercurials and the relative amounts of catalytic (C) and regulatory (R) subunits were determined by three methods: (a) quantitative cellulose acetate electrophoresis; (b) Lowry analysis after separating the catalytic and regulatory subunits by sucrose gradient centrifugation; (c) dissociation of the species with sodium dodecyl sulfate and determination of the relative amounts of catalytic and regulatory chain by sodium dodecyl sulfate gel electrophoresis. All three methods gave consistent results, indicating that the molecule consists of 75% (by weight) catalytic chain and 25% regulatory chain. The molecular weight determined by gel filtration, sedimentation velocity, and sedimentation equilibrium experiments was found to be approximately 270,000. These observations establish that this species has the structure C6R4, and is produced by the release of a single regulatory dimer R2 from the intact aspartate transcarbamylase complex. This protein (C6R4) contains 20 cysteines and four zinc ions, consistent with the proposed subunit structure. The purified intermediate C6R4 contains no mercury. The parent molecule C6R6 can be reconstituted from C6R4 by incubation with isolated regulatory subunit (R2) in the presence of zinc and beta-mercaptoethanol. Titration of C6R4 yields an end point which corresponds to the addition of 1 mol of regulatory subunit (R2) per mol of C6R4. The intermediate is quite stable at neutral pH but tends to disproportionate into aspartate transcarbamylase and catalytic subunit after prolonged storage or at elevated pH. The kinetic properties of this species have been investigated. The specific activity of C6R4 is virtually identical with that of the native enzyme but the regulatory properties are substantially reduced. Both homotropic and heterotropic interactions are reduced but not abolished, indicating that the intact structure C6R6 is not required for the allosteric transitions involved in regulation.

Adenosine Triphosphate↗
PubMed1975

Development of a reaction inventory to measure guilt.

The Reaction Inventory-Guilt was developed to isolate, in individuals, the specific stimulus situations which result in guilt. The 50-item inventory was administered to 96 subjects. The estimate of the internal consistency coefficient was .94. The inter-item correlations were factor analyzed by the principle axis method, and rotation to oblique simple structure was accomplished by the Promax method. Four oblique factors were obtained: intentional behavior disrupting interpersonal relations; self-destructive behavior; behavior contrary to moral or ethical principles; and unintentional behavior disrupting interpersonal relationships.

Adolescent↗
PubMed1974

Complex of aspartate carbamoyltransferase from Escherichia coli with its allosteric inhibitor, cytidine triphosphate: electron density at 5.9-angstroms resolution.

Following our earlier determination of the three-dimensional structure of aspartate carbamoyltransferase (EC 2.1.3.2; carbamoylphosphate: L-aspartate carbamoyltransferase) to 5.5-A resolution [S. G. Warren, B. F. P. Edwards, D. R. Evans, D. C. Wiley & W. N. Lipscomb (1973) Proc. Nat. Acad. Sci. USA 70, 1117-1121], we report here, from a different crystal form, the three-dimensional structure at 5.9 A of this enzyme complexed with its allosteric inhibitor, cytidine triphosphate. Location of the major binding site of this inhibitor within each of the six regulatory chains is made secure by comparison of these results with those obtained upon binding of 5-iodocytidine triphosphate to the enzyme. Conformational changes in the aspartate carbamoyltransferase molecule when this inhibitor binds are described briefly at 5.9-A resolution.

Allosteric Regulation↗
PubMed1974

An intermediate complex in the dissociation of aspartate transcarbamylase.

The multisubunit enzyme aspartate transcarbamylase consists of six copies of two types of polypeptide chains, catalytic (C) and regulatory (R). A complex formed by the partial dissociation of this enzyme has been isolated. This species, which has the structure C(6)R(4), is a likely intermediate in the stepwise dissociation of aspartate transcarbamylase induced by mercurials. The formation of the complex is the result of the release of a single regulatory dimer (R(2)) from the parent molecule.The specific activity of the intermediate is essentially the same as that of aspartate transcarbamylase. By contrast, both homotropic and heterotropic interactions are reduced, but not abolished. These observations suggest that the allosteric transitions involved in the control mechanisms do not require the intact structure C(6)R(6).

Allosteric Regulation↗
PubMed1973

Aqueous central cavity in aspartate transcarbamylase from Escherichia coli.

A three-dimensional x-ray diffraction study of aspartate transcarbamylase to 5.5-angstrom resolution, with the aid of four isomorphous heavy atom derivatives, indicates the presence of a central aqueous cavity approximating an oblate spheroid about 25 by 50 by 50 angstroms in dimension, within a molecule about 90 by 110 by 110 angstroms in largest dimensions.

Aspartate Carbamoyltransferase↗
PubMed1973

Aspartate transcarbamoylase from Escherichia coli: electron density at 5.5 A resolution.

The allosteric enzyme, aspartate transcarbamoylase (EC 2.1.3.2), has previously been shown in our x-ray diffraction studies to have D(3)-32 symmetry. There are six catalytic (C) and six regulatory (R) chains in the molecular complex (R(6)C(6)). Our three-dimensional x-ray diffraction study of this enzyme (R32, a = 131 A, c = 200 A) at 5.5 A resolution shows a spatial arrangement of the two catalytic trimers C(3) above and below an equatorial belt of three regulatory dimers R(2). The molecule is about 110 x 110 x 90 A in largest dimensions, and is shown here to contain a large central aqueous cavity about 50 x 50 x 25 A in size. Location of the single sulfhydryl of each catalytic chain, and correlation of its reactivity with enzymatic activity in the molecule, suggests that the nearby active sites are most probably accessible from the central cavity, but probably not directly from the external solution. The most obvious access to the central cavity consists of six channels, each about 15 A in diameter, near the regulatory region. A component of the regulatory mechanism may be modulation of access of substrates through these channels.

Allosteric Regulation↗