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Biomedical subjects

J R Walker

Publications and source records attributed to J R Walker.

At least 37 records · Page 2Linked to original sources
PubMed2000

Perfectionism and chronic insomnia.

The relationship between chronic insomnia and perfectionism was investigated using a sample of 32 adults with chronic insomnia and 26 healthy controls. Different aspects of perfectionism were measured using two Multi-Dimensional Perfectionism Scales [Frost RO, Marten P, Lahart C, Rosenblate R. The dimensions of perfectionism. Cognit Ther Res 1990;14(5):449-468; Hewitt PL, Flett GL. The Multidimensional Perfectionism Scale: development and validation. Can Psychol 1989;30:339; Hewitt PL, Flett GL. Perfectionism in the self and social contexts: conceptualization, assessment, and association with psychopathology. J Pers Soc Psychol 1991;60:456-470.]. Using a univariate approach, results indicated that those with chronic insomnia were more likely to endorse features of "maladaptive" perfectionism relative to healthy controls. Further, those with chronic insomnia were more likely to report doubts about action, frequent parental criticism, and concern over mistakes. Although those with chronic insomnia were found to be more perfectionistic in these areas, only perception of heightened parental criticism was associated with the reporting of delayed sleep-onset latency. No other aspect of perfectionism was associated with sleep-onset latency, total sleep time, or sleep quality. Implications for theories of the development of insomnia are discussed.

Adaptation, Psychological↗
PubMed2000

A program evaluation study of a nursing home operated as a modified therapeutic community for chemically dependent persons with AIDS. Project Samaritan AIDS Services, Inc.'s Residential Health Care Facility, Highbridge Section, Bronx, NY.

An interagency evaluation of the treatment effectiveness of a speciality nursing home (NH) run as a therapeutic community (TC) for residents diagnosed with acquired immunodeficiency syndrome (AIDS) and substance abuse/dependence (SA/D) was conducted. A total of 79 chemically dependent men and women with AIDS were: (a) administered the Tennessee Self-Concept Scale (TSCS; Roid & Fitts, 1991) at initial testing (T(1)) and 8 months after their initial testing (T(2)); and (b) assessed on specific physical health indicators (i.e. , weight, CD-4 count, and viral load) and other treatment outcomes (e.g., abstinence) over the same two time periods. The TSCS results identified a valid and invalid TSCS test group and further distinguished among three subgroups of invalid responders. Significant improvements were observed from T(1) testing to T(2) testing on the TSCS, on the physical health indicators, and on other treatment outcomes. The need for additional and continued mental health services for this population was noted.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Persistent increase in the motivation to take heroin in rats with a history of drug escalation.

The transition from stable to escalated levels of cocaine self-administration has been shown to depend upon drug availability. The generality of this phenomenon is assessed here by studying the effects of availability on heroin self-administration. Two groups of rats were trained on a 1-h continuous schedule of self-administration, after which, access to heroin (40 microg/injection) was increased to 11 h in one group (long access or LgA rats) or kept to 1 h in the other group (short access or ShA rats). After 18 sessions on this regimen, both ShA and LgA rats were tested for extinction and stress-induced reinstatement of heroin-seeking behavior. In LgA rats, both total and first hour intake gradually escalated over time. After escalation, LgA rats were slower to extinguish heroin-seeking behavior and responded more to the reinstating effect of stress after extinction. These findings show that: (1) the escalation process in drug consumption is common to both opiate and stimulant self-administration; (2) escalation in heroin consumption is associated with a persistent increase in the motivation for taking heroin.

Animals↗
PubMed2000

Suppression of a DnaX temperature-sensitive polymerization defect by mutation in the initiation gene, dnaA, requires functional oriC.

Temperature sensitivity of DNA polymerization and growth, resulting from mutation of the tau and gamma subunits of Escherichia coli DNA polymerase III, are suppressed by Cs,Sx mutations of the initiator gene, dnaA. These mutations simultaneously cause defective initiation at 20 degrees C. Efficient suppression, defined as restoration of normal growth rate at 39 degrees C to essentially all the cells, depends on functional oriC. Increasing DnaA activity in a strain capable of suppression, by introducing a copy of the wild-type allele, increasing the suppressor gene dosage or introducing a seqA mutation, reversed the suppression. This suggests that the suppression mechanism depends on reduced activity of DnaACs, Sx. Models that assume that suppression results from an initiation defect or from DnaACs,Sx interaction with polymerization proteins during nascent strand synthesis are proposed.

Bacterial Proteins↗
PubMed2000

Prevention of relapse in generalized social phobia: results of a 24-week study in responders to 20 weeks of sertraline treatment.

The aim of this study was to evaluate the efficacy, tolerability, and effects on quality of life of sertraline, a selective serotonin reuptake inhibitor, in the prevention of relapse of generalized social phobia. Fifty adult outpatients with generalized social phobia who were rated much or very much improved on the Clinical Global Impression Scale of Improvement (CGI-I) after 20 weeks of sertraline treatment (50-200 mg/day) were randomly assigned in a one-to-one ratio to either continue double-blind treatment with sertraline or immediately switch to placebo for another 24 weeks. The initial 20-week study was placebo-controlled, and 15 responders to placebo also continued to receive double-blind placebo treatment in the continuation study. Eighty-eight percent of patients in the sertraline-continuation group and only 40% of patients in the placebo-switch and placebo-responder groups completed the study. In intent-to-treat endpoint analyses, 1 (4%) of 25 patients in the sertraline-continuation group and 9 (36%) of 25 patients in the placebo-switch group had relapsed at study endpoint (chi2 = 8.0, Fisher exact test, p = 0.01). The relative risk (hazards ratio) for relapse associated with placebo-switch relative to sertraline-continuation treatment was 10.2 (95% confidence interval, 1.3-80.7). Mean CGI-Severity, Marks Fear Questionnaire (MFQ) Social Phobia subscale, and Duke Brief Social Phobia Scale (BSPS) total scores were reduced by 0.07, 0.34, and 1.86 in the Sertraline-Continuation group and increased by 0.88, 4.09, and 5.99 in the Placebo-Switch group (all F > 5.3, p < 0.03), respectively. CGI-Severity, MFQ Social Phobia subscale, and BSPS scores also increased in the Placebo-Responder group. Discontinuations because of lack of efficacy were 4% in the sertraline-continuation group, 28% in the placebo-switch group (chi2 = 5.36, Fisher exact test, p = 0.049), relative to sertraline, and 27% in the placebo-responder group. Sertraline was effective in preventing relapse of generalized social phobia. Future research should assess whether improvements may be maintained or further increased by longer periods of treatment or through the addition of cognitive-behavioral techniques.

Adult↗
PubMed2000

Escherichia coli DNA polymerase III tau- and gamma-subunit conserved residues required for activity in vivo and in vitro.

The Escherichia coli DNA polymerase III tau and gamma subunits are single-strand DNA-dependent ATPases (the latter requires the delta and delta' subunits for significant ATPase activity) involved in loading processivity clamp beta. They are homologous to clamp-loading proteins of many organisms from phages to humans. Alignment of 27 prokaryotic tau/gamma homologs and 1 eukaryotic tau/gamma homolog has refined the sequences of nine previously defined identity and functional motifs. Mutational analysis has defined highly conserved residues required for activity in vivo and in vitro. Specifically, mutations introduced into highly conserved residues within three of those motifs, the P loop, the DExx region, and the SRC region, inactivated complementing activity in vivo and clamp loading in vitro and reduced ATPase catalytic efficiency in vitro. Mutation of a highly conserved residue within a fourth motif, VIc, inactivated clamp-loading activity and reduced ATPase activity in vitro, but the mutant gene, on a multicopy plasmid, retained complementing activity in vivo and the mutant gene also supported apparently normal replication and growth as a haploid, chromosomal allele.

Adenosine Triphosphatases↗
PubMed2000

Fear: the impact and treatment of social phobia.

Social phobia is the most common anxiety disorder in the community with a prevalence rate in the range of 5-8%. The problem most often emerges in childhood or adolescence. Individuals with generalized social phobia are at risk of developing other psychiatric disorders such as major depression, alcohol abuse and other anxiety disorders. Sufferers of social phobia often do not seek treatment until they encounter difficulty with comorbid disorders. Recent research indicates that social anxiety disorder is associated with higher levels of disability and greater reductions in quality of life than previously understood, with difficulties encountered in social relationships, education and employment. In previous years, there has been little or no known available effective treatment, and the disorder frequently goes unrecognized in primary care. However, new pharmacological (selective serotonin reuptake inhibitors, SSRIs) and psychological treatments are emerging that are able to produce significant symptom reduction and improvements in functioning and quality of life. In recent years, the SSRIs have been the focus of considerable research and are becoming one of the first-line treatments for social phobia. Early intervention in social phobia may improve quality of life, reduce disability and reduce the development of comorbid disorders.

Cognitive Behavioral Therapy↗
PubMed1999

Antagonism of heroin and morphine self-administration in rats by the morphine-6beta-glucuronide antagonist 3-O-methylnaltrexone.

In mice, 3-O-methylnaltrexone blocks the analgesic actions of morphine-6beta-glucuronide and heroin at doses which are inactive against morphine. We found a similar selectivity in rats. 3-O-Methylnaltrexone antagonized the analgesic actions of 6-acetylmorphine in Sprague-Dawley rats and heroin in Wistar rats at doses that were inactive against morphine. Inclusion of a fixed dose of 3-O-methylnaltrexone significantly shifted the analgesic dose-response curves for 6-acetylmorphine and heroin without altering the morphine dose-response curves. In a self-administration model, 3-O-methylnaltrexone treatment significantly increased both heroin and morphine intake during the first hour, suggestive of an antagonist effect. This effect at doses of 3-O-methylnaltrexone which were inactive against morphine analgesia implied a role for the morphine-6beta-glucuronide opioid receptor in the reinforcing properties of heroin and morphine.

Animals↗
PubMed1999

Local and systemic therapy of human prostate adenocarcinoma with the conditionally replicating herpes simplex virus vector G207.

Prostate adenocarcinoma is the most common nonskin malignancy in males and the second most common cause of cancer death in the United States (Landis et al., 1998). Initial treatments of surgery or radiotherapy may cause impotence and/or incontinence from neural damage (Eastham and Scardino, 1998; Porter et al., 1998). When extraprostatic or metastatic disease develops, castration or pharmaceutical androgen ablation is utilized (Catalona, 1994). Androgen-resistant recurrence indicates a poor prognosis and justifies experimental chemotherapy (Oh and Kantoff, 1998). G207 (Mineta et al., 1995; Yazaki et al., 1995) is a multimutated herpes simplex virus 1 (HSV) vector that replicates within cancer cells, causing cellular death; however, replication is limited in normal cells, including those of the nervous system. In vitro, G207 at a low multiplicity of infection (MOI of 0.01) is oncolytic for multiple human prostate cancer cells. In athymic mice, a single intraneoplastic inoculation of G207 completely eradicates >22% of established subcutaneous human prostate cancer tumors irrespective of hormonal responsiveness. Two intraneoplastic inoculations of G207 completely eradicated two of three recurrent previously irradiated tumors and two intravenous administration of G207 induced tumor regression in distant subcutaneous tumors and completely eradicated one-fourth of the tumors.

Adenocarcinoma↗
PubMed1999

A comparison of people with and without nocturnal panic attacks.

This study examined differences in frequency and severity of diurnal panic attacks between patients with (n = 22) and without (n = 21) a history of nocturnal panic attacks. Subjects were assessed with a modified version of the SCID, and completed daily panic attack diaries, the Anxiety Sensitivity Index, and the Fear Questionnaire. No differences were found between the groups in the actual number of expected or unexpected diurnal panic attacks experienced. Subjects in the nocturnal panic group experienced significantly more symptoms during diurnal panic attacks than did the diurnal only group. More specifically, the nocturnal panic group experienced more symptoms during expected diurnal panic attacks, but not during unexpected/spontaneous diurnal panic attacks. A greater proportion of the nocturnal panic subjects reported "chest pain" during diurnal panic attacks and a trend toward greater "fear of dying". Otherwise, the two groups were very similar. Implications of the findings are discussed in relation to the findings of other recent studies of nocturnal panic.

Adult↗
PubMed1999

Anesthetic implications of illicit drug use.

Individuals who abuse illicit drugs have an increased incidence of traumatic injury, medical illness, and drug overdose. Subsequently, many of these drug abusers will require perianesthesia care. The health care professionals responsible for their care must have an understanding of the prevalence, the pharmacology, and medical complications of illicit drug use, including the potential interactions with anesthetic agents.

Anesthetics↗
PubMed1999

Antihypertensive agents.

Fifty million Americans suffer from hypertension. During the perioperative period, hypertension is a frequent finding owing to a variety of mechanisms including anxiety, pain, and preexisting conditions. This article explores the pharmaceutical agents commonly used in the treatment of hypertension. Particular attention is directed to drugs administered in the perioperative setting and complications that can be observed.

Antihypertensive Agents↗
PubMed1999

Anesthesia for cardioversion.

Elective electrical cardioversions are commonly scheduled to be performed in the PACU because of the availability of nursing and anesthesia support. This report examines preanesthetic patient preparation as well as a review of the procedural aspects of electrical cardioversion. The commonly used anesthetic agents are contrasted with regard to their pharmacodynamic considerations. The indications, contraindications, and complications associated with the procedure are reviewed.

Anesthesia↗
PubMed1998

Nociceptin fails to affect heroin self-administration in the rat.

The recently isolated peptide nociceptin has a primary structure similar to that of opioid peptides. Early functional studies suggested that it may act in opposition to opioid systems. To determine whether nociceptin influences the rewarding properties of heroin, nociceptin was given intracerebroventricularly (i.c.v.) to rats trained to self-administer heroin. Rats (n = 8) were given doses of 0.01 microg, 0.1 microg, 1.0 microg and 10.0 microg in a Latin square design. None of the doses significantly affected heroin self-administration rates compared to vehicle. The highest dose of nociceptin used inhibited spontaneous locomotor activity, evidence that the peptide retained its biological activity after i.c.v. infusion. These studies suggest that nociceptin does not affect the rewarding value of heroin.

Animals↗
PubMed1998

Developmental changes in refractoriness of the neuromagnetic M100 in children.

Considerable evidence exists for developmental changes in latency and amplitude of the auditory evoked potential termed N100. However, it is widely recognized that the N100 wave comprises multiple, temporally overlapping neural generators, and few data are available addressing either individual generator development or mechanisms behind such change. Using magnetoencelphalographic (MEG) measurements of the magnetic analog of the N100 termed the M100, which derives primarily from supra-temporal auditory generators, it is demonstrated here that changes in the response of that waveform to manipulation of interstimulus interval (ISI) occur between the ages of 6 and 18 years of age.

Adolescent↗
PubMed1998

Chimeric CD4/CD44 molecules associate with CD44 via the transmembrane region and reduce hyaluronan binding in T cell lines.

Cells of the immune system tightly regulate the binding ability of cell adhesion molecules. The binding of the extracellular matrix component hyaluronan to CD44 is no exception, yet the mechanisms that regulate its binding are poorly understood. In this study a chimeric CD4/CD44 molecule, containing the extracellular domain of CD4 and the transmembrane and cytoplasmic domains of CD44, was expressed in two CD44+ mouse T lymphoma cell lines, BW5147 and T28. This resulted in the reduced ability of endogenous CD44 to constitutively bind hyaluronan. Immunoprecipitation of the chimeric protein in 1 % Brij-96 indicated an association between the chimera and endogenous CD44. Using various chimeric CD4/CD44 molecules, the transmembrane region of CD44 was found to mediate this association. In addition, the association of chimeric CD4/CD44 molecules with endogenous CD44 correlated with reduced hyaluronan binding. Thus, the transmembrane region of CD44 is required for the association with CD44 molecules in the cell membrane and we propose that the self-association of CD44 molecules occurs on the T cell surface to promote hyaluronan binding. Cellular events altering the interactions of the transmembrane region of CD44 thus have the potential to regulate the hyaluronan binding ability of CD44.

3T3 Cells↗