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Biomedical subjects

D Denney

Publications and source records attributed to D Denney.

At least 19 recordsLinked to original sources
PubMed1999

Theorizing about nurses' work lives: the personal and professional aftermath of living with healthcare 'reform'.

In this paper we discuss the impact of healthcare 'reform' on nurses' personal and professional lives. Using a thematic analysis, we interviewed 38 nurses in Nova Scotia, Canada regarding their experiences of job displacement, inability to find full-time employment and job losses. Their stories reflect how they lived day by day and the effects this had on their children, partners, friends and leisure, as well as their financial burdens. We theorize about the relationship between nurses' work and women's work, and particularly about women working in unstable conditions and the impact on their lives and that of the clients with whom they work.

Adaptation, Psychological↗
PubMed1998

A cross-cultural study of reactivation of posttraumatic stress disorder symptoms: American and Cambodian psychophysiological response to viewing traumatic video scenes.

A physiological hyperarousal state, which can be reactivated by traumatic stimuli, occurs frequently in patients with posttraumatic stress disorder (PTSD). The goals of this study were to determine whether physiological hyperarousal measured by increased heart rate is a specific response to reminders of a patient's own traumatic events or a more generalized hyperarousal state. Five brief videotape scenes of traumatic events (hurricane, auto accident, Cambodian refugee camp, domestic violence, and Vietnam War) were shown to two patient groups with PTSD (Vietnam veterans and Cambodian refugees) and three control groups (Vietnam veterans, Cambodian refugees, and nonpatient Americans). Observations of subjects' behavior, subjective ratings of distress, and heart rate change were recorded and evaluated. The results indicated that Cambodians with PTSD had the most reactions as measured by behavior and heart rate changes. These tended to occur during all scenes, not just the specific Cambodian scene, indicating a general nonspecific arousal. The Vietnam veterans had the fewest changes implying an inhibition of response. The control groups were intermediate in physiological response. The response in PTSD patients to reactivation scenes is complex and probably relates to type and degree of trauma, as well as to culture.

Adult↗
PubMed1997

Sensitization with clozapine: beyond the dopamine hypothesis.

Clozapine elicits dose-dependent myoclonic jerks in partially restrained rats and induces paroxysmal electroencephalographic changes, myoclonus, and convulsive seizures in a small but significant percentage of patients. With the hypothesis that the central excitatory effects of clozapine may relate to the unique therapeutic activity of this agent, rats were administered repeated alternate day or weekly very low dose (1 mg/kg) injections of clozapine in an attempt to induce the central excitatory effect through sensitization or kindling. Although initial administrations of this dose elicited no motor response or other behavioral change, repeated administration of the same low dose on either the alternate-day or weekly schedule caused increasing numbers of myoclonic seizure-like jerks (MJs) reaching 75-110 MJs/hour by the sixth clozapine injection. Clozapine-sensitized animals exhibited a significantly different pattern of early gene expression in two subcortical sites compared with vehicle-treated controls. These findings may have importance for the treatment of psychosis.

Animals↗
PubMed1996

Kindling with clozapine: behavioral and molecular consequences.

Clozapine is an 'atypical' neuroleptic that improves symptoms of many patients with schizophrenia whose illness is resistant to treatment with other neuroleptics. Unlike the 'typical neuroleptics (chlorpromazine, haloperidol), clozapine does not induce extrapyramidal symptoms such as Parkinsonism and tardive dyskinesia in humans or catalepsy in the rat. However, clozapine frequently causes epileptiform EEG changes and causes seizures in 3-5% of patients treated with this drug in therapeutic doses. Clozapine also induces dose dependent myoclonus in the partially restrained rat. In the experiments reported here, partially restrained rats were administered repeated alternate day or weekly low, fixed doses of clozapine (1 mg/kg). This dose initially caused no behavioral change. Following the third and subsequent administrations, the same dose elicited an increasing number of myoclonic seizure-like jerks reaching 140/h following the 15th injection in rats receiving the same low dose of clozapine on alternate days and 160/h following the 9th injection in animals that received the same dose once weekly. These effects are consistent with kindling, i.e. a progressive increase of brain excitability following repeated administration of a fixed subconvulsive dose of an excitatory agent. Clozapine kindled animals exhibited a significantly different pattern of early gene expression in ventral tegmental area, origin of the mesolimbic-mesocortical dopamine system and in the anterior thalamic nuclei, compared with saline treated controls subjected to exactly the same recording conditions. The evidence of central nervous system excitation with clozapine may be important to the unique therapeutic effect of this atypical antipsychotic in the treatment of symptoms, especially the deficit symptoms, of schizophrenia.

Animals↗
PubMed1995

Clozapine and seizures.

Epileptiform EEG changes, myoclonus, and seizures are reported in some patients treated with clozapine. Although these are undesirable side effects, the excitation of specific neuronal networks by clozapine and other neuroleptics may be important for the therapeutic effect of this class of agents. In these experiments, intraperitoneal clozapine 2-16 mg/kg produced dose-related myoclonic jerks in partially restrained rats. Paroxysmal slow waves and spike activity were recorded from implanted electrodes in amygdala, hippocampus, and cortex following higher doses of clozapine, but the EEG abnormalities were not correlated with the myoclonic jerks. Single doses of chlorpromazine (8 and 16 mg/kg) rarely produced myoclonic jerks but provoked generalized tonic seizures in two animals preceded by multiple myoclonic jerks in one. Myoclonus and seizures reflect increased excitability of the central nervous system. It is possible that clozapine and other neuroleptics exert a therapeutic effect by increasing excitability in critical subcortical areas of the brain.

Amygdala↗
PubMed1993

Formation of phenol and thiocatechol metabolites from bromobenzene premercapturic acids through pyridoxal phosphate-dependent C-S lyase activity.

When N-acetyl-S-(2-hydroxy-4-bromocyclohexa-3,5-dienyl)-L-cystein e (4-S-premercapturic acid) and N-acetyl-S-(2-hydroxy-5-bromocyclohexa-3,5-dienyl)-L-cystein e (3-S-premercapturic acid) were used as substrates in incubations with Hartley guinea pig kidney 9000 g supernatant preparations, the major products were the corresponding S-(2-hydroxy-4-bromocyclohexa-3,5-dienyl)-L-cysteine and S-(2-hydroxy-5-bromocyclohexa-3,5-dienyl)-L-cysteine. At the end of the incubation period, the percentage recovery of these N-deacetylate cysteine conjugates accounted for 77 +/- 2% of the substrates, 3-S- and 4-S-premercapturic acids. Removal of the N-acetyl group from premercapturic acids to form the corresponding cysteine conjugates by kidney N-deacetylase(s) showed no preference with respect to the 3-S- and 4-S-positional isomeric conjugates. Other metabolites which included the known sulfur-containing acids, mercaptolactate and mercaptoacetate, were also detected. 3- and 4-Bromophenol and 3- and 4-bromothioanisole were also formed. The addition of pyridoxal-5'-phosphate to the kidney incubation mixture resulted in a 5-fold increase in the formation of phenols and thioanisoles, along with four different isomeric O- and S-methylated 3-S-and 4-S-bromothiocatechols and two S-methylated 3-S- and 4-S-bromodihydrobenzene thiolols. This result indicated that a pyridoxal phosphate-dependent C-S lyase(s) is involved in the formation of both phenol and thiophenolic metabolites from S-(2-hydroxy-4-bromocyclohexa-3,5-dienyl)-L-cysteine and S-(2-hydroxy-5-bromocyclohexa-3,5-dienyl)-L-cysteine. Guinea pig liver 9000 g supernatant preparations did not N-deacetylate the 3-S- and 4-S-premercapturic acids to the same extent as kidney preparations, and this may account for decreased conversion of 3-S- and 4-S-premercapturic acids to 3- and 4-bromophenol and to thiophenolic products by liver preparations.

Animals↗
PubMed1990

Subtractive hybridization system using single-stranded phagemids with directional inserts.

We describe a subtractive hybridization protocol which is designed to permit subtractions between cDNA libraries. The method uses single-stranded phagemids with directional inserts as both the driver and the target. We modified the M13 phagemid vector pBluescript for the directional cDNA cloning and subtractive hybridization. Two simplified methods for efficient construction of directional cDNA libraries are also described. Using a model system, we found that one round of subtractive hybridization results in a 5,000-fold specific subtraction of abundant molecules. We used two methods to quantify the efficiency and verify the specificity of the subtraction. In order to obtain these subtraction efficiencies, it was necessary to develop a method to purify the single-stranded DNA to homogeneity. The single-stranded purification involved using potassium iodide (KI) density centrifugation, restriction endonuclease digestion and phenol extraction in the presence of magnesium. We describe the several advantages of using directional inserts for the subtraction procedure.

Bacteriophages↗
PubMed1987

Molecular mapping of class II polymorphisms in the human major histocompatibility complex. I. DR beta.

We have studied 27 cell lines homozygous by consanguinity for the major histocompatibility complex to establish the restriction fragment length polymorphism (RFLP) patterns seen with six different restriction enzymes (Bam HI, Bg1 II, Eco RI, Hinc II, Hind III, Pvu II) and DR beta chain probes. The probes used were a full-length cDNA DR beta probe and a probe specific for the 3' untranslated region. The RFLP obtained represent the first standard patterns for the individual haplotypes DR1 through 7 and DR9 as defined by genetically homozygous lines. The patterns obtained reflect the DR specificities closely, as well as the DRw52 and DRw53 specificities. These latter specificities are associated with the most prominent patterns of RFLP. Bands are present which are unique for the haplotypes DR1, DR2, DR4, DR7, DRw52, and DRw53, and could be used for typing these haplotypes in heterozygotes. Subtypes can be identified for all of the haplotypes except DR1. These subtypes indicate that there is an extensive amount of polymorphism in the DR subregion that has not been identified serologically.

Cell Line↗
PubMed1987

Molecular mapping class II polymorphisms in the human major histocompatibility complex. II. DQ beta.

The restriction fragment length polymorphisms have been determined for six restriction enzymes (Bam HI, Bg1 II, Eco RI, Hinc II, Hind III, and Pvu II) and a DQ beta probe on 25 cell lines that are homozygous by consanguinuity at the MHC. These patterns reflect both DR haplotypes and DQ types of the cells tested. At least one non-polymorphic band is present in all the cell lines with every restriction enzyme except Hinc II. This band most probably represents DX beta hybridization. The polymorphic bands indicate that more polymorphism exists in the DQ subregion than is predicted serologically. Each DR haplotype is associated with a unique set of restriction fragments except for DR2 and DR6. The patterns are largely consistent within each DR haplotype. In addition, some bands reflect the established DQ specificities DQw1 and DQw2. Individual bands can be identified that are unique to the haplotypes DR1, DR4, DR5, and DR6 and the DQw1- and DQw2-associated haplotypes. Subdivisions of haplotypes can be identified with this probe. In particular, MVL (DR1), Akiba (DR2), QBL (DR3), FPF (DR5), and APD (DR6) have polymorphisms that distinguish them from other members of their DR haplotype.

Cell Line↗
PubMed1987

Allelic variation in the DR subregion of the human major histocompatibility complex.

Allelic variation in the DR subregion of the human major histocompatibility complex has been analyzed by nucleic acid sequencing of cDNA clones obtained from cell lines homozygous by consanguinity for all the common serological types DR1-9. Two expressed loci were identified in the haplotypes DR2, -3, -4, -7, and -9; one locus being present at a much lower frequency (4-7%) than the other. The low-frequency allele was highly conserved between each of the DRw53 (DR4, -7, -9) and the DRw52 (DR3, -5, -6) haplotypes. Analysis of the variation between alleles confirms the presence of three allelic hypervariable regions. At each variable residue, a limited range of amino acid substitutions are found, distinguishing them from immunoglobulin hypervariable regions. Dinucleotide substitutions are extremely common. Individual hypervariable regions are often shared between haplotypes. Much of the variation in these alleles can be attributed to the shuffling of these regions between haplotypes, possibly by the mechanism of gene conversion.

Alleles↗
PubMed1984

The eye blink electro-oculogram.

An electro-oculogram (EOG) was derived from potentials recorded from electrodes placed above and below the eye during voluntary vertical eye movements. Concurrent measurement of the amplitude of eye blink potentials recorded from the same electrodes produced curves which were highly correlated with the EOG measured from stereotyped eye movements. Recordings from a patient with a missing globe, owing to trauma, revealed eye movement and blink responses only from the intact side. A patient with no light perception showed blink responses which were less variable than responses measured during attempts voluntarily to move the eyes vertically in 60 degrees excursions. An EOG calculated by measurement of eye blink potentials may be possible in clinical situations where traditional electro-oculography techniques are not feasible.

Adaptation, Ocular↗
PubMed1979

Telemetered EEG-EOG during psychotic behaviors of schizophrenia.

In an effort to establish correlations between abnormal behaviors characteristic of schizophrenia and simultaneous cerebral electrical activity, EEGs and electro-oculograms (EOGs) were continuously recorded for 2 to 24 hours by radiotelemetry from 40 patients with schizophrenia and 12 normal control subjects. Trained observers recorded specific behavior patterns permitting visual and computer analysis of EEG during hallucinations, stereotypy, catatonia, psychomotor blocking, and other characteristic manifestations of schizophrenia. Electroencephalographic abnormalities consisting of focal slow or spike activity over either temporal region were found in nearly half of the patients so recorded. In contrast to the EEG during ictal episodes of epilepsy, the abnormal wave forms of schizophrenic patients seldom coincided with episodes of blocking, stereotypy, or other abnormal behaviors. Increased extraocular activity or blinking were recorded in a majority of patients, but were not consistently associated with the abnormal behavior or perceptual events.

Adult↗
PubMed1977

Pharmacological characterization of tardive dyskinesia.

Tardive dyskinesia (TD) may be a clinical manifestation of a relative imbalance between the inversely related dopaminergic (DA) and acetylcholinergic (ACh) influences in the central nervous system (CNS). Six patients were evaluated with single challenge doses of a DA agonist, levodopa, and antagonist, droperidol, as well as with an ACh agonist, physostigmine, an antagonist, benztropine, and a placebo. A single blind trial with deanol and placebo followed. Responses, measured by an electrophysiological technique, formed two subgroups. The patients who improved with a DA antagonist or an ACh agonist improved while taking deanol. Another group of patients were made worse with a DA antagonist or ACh agonist and were worsened or had no response while taking deanol. While the results add support to the concept of counterbalancing DA-ACh influences in TD, further investigation of TD subtypes and predictors of drug response is warranted.

Adult↗