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C Dean

Publications and source records attributed to C Dean.

At least 145 records · Page 8Linked to original sources
PubMed1992

Development of an efficient two-element transposon tagging system in Arabidopsis thaliana.

Modified Ac and Ds elements, in combination with dominant markers (to facilitate monitoring of excision, reinsertion and segregation of the elements) were introduced into Arabidopsis thaliana ecotype Landsberg erecta. The frequencies of somatic and germinal transactivation of the Ds elements were monitored using a streptomycin resistance assay. Transactivation was significantly higher from a stable Ac (sAc) carrying a 537 bp deletion of the CpG-rich 5' untranslated leader of the transposase mRNA than from a wild-type sAc. However, substitution of the central 1.77 kb of the transposase open reading frame (ORF) with a hygromycin resistance marker did not alter the excision frequency of a Ds element. beta-Glucuronidase (GUS) or iaaH markers were linked to the transposase source to allow the identification of plants in which the transposase source had segregated away from the transposed Ds element, eliminating the possibility of somatic or germinal re-activation. Segregation of the excision marker, Ds and sAc was monitored in the progeny of plants showing germinal excision of Ds. 29% of the plants inheriting the excision marker carried a transposed Ds element.

Blotting, Southern↗
PubMed1992

Differential control of sympathetic activity to kidney and skeletal muscle by ventral medullary neurons.

A rise in arterial blood pressure can be evoked by microinjections of D,L-homocysteic acid into localized regions of the ventrolateral medulla of the cat. Three patterns of sympathetic discharge can be identified during the pressor response. A differential pattern consisting of an increase in renal nerve activity and no change in sympathetic activity to skeletal muscle vasculature can be elicited from sites ventromedial to the caudal pole of the facial nucleus. From more lateral and caudal sites, a generalized sympatho-excitation is evoked in the outflow to both the kidney and hindlimb muscle vasculature. A third response consisting of a differential increase in muscle sympathetic activity simultaneous with a small decrease in renal nerve activity could be evoked from caudal sites, lateral to the inferior olives and superficial to the ventral surface. The results show that ventral medullary neurons can selectively activate sympathetic outflow to control specific vascular beds. These data may support the hypothesis that the ventrolateral medulla contains discrete groups of topographically arranged neurons that can differentially control sympathetic tone to various end-organs.

Animals↗
PubMed1992

Psychiatric and social consequences of liver transplantation.

We assessed the prevalence of psychiatric morbidity and level of social adjustment in 32 of 34 adults who received liver transplants between 1 August 1987 and 31 July 1988 and who survived more than 6 months postoperatively. The prevalence of psychiatric morbidity was comparable with that found in the general population. Subjective complaints of cognitive impairment were common (40.6%). Liver transplant recipients were not significantly more handicapped in overall social functioning, but did show significant impairment in several role areas when compared with a community sample. Psychiatric morbidity was associated with greater social impairment, whereas liver function and other medical problems were not. We suggest that identification and treatment of psychiatric illness following transplantation needs to be better established as part of the treatment program.

Adult↗
PubMed1992

Acute resetting in two functionally different types of carotid baroreceptors.

The presence of two types of carotid sinus baroreceptors, as characterized by two different stimulus-response curves in an earlier study, suggests that each type may play a different role in the regulation of blood pressure. The discontinuous hyperbolic curve of the type I baroreceptors, marked by higher firing rates and greater sensitivity than the sigmoidal curve of type II baroreceptors, suggests that these baroreceptors would contribute more to the buffering of arterial pressure changes than the "tonically" active type II baroreceptors, which fired over greater pressure ranges and generally had spontaneous subthreshold discharge. The firing characteristics of type II baroreceptors suggest that these receptors would contribute more to regulation of tonic, baseline levels of arterial pressure. If this functional differentiation exists, the acute resetting characteristics of the two types of baroreceptors could be different. Resetting is defined as a shift in the response curve of a baroreceptor, marked by shifts in pressure threshold, in the same direction as the change in pressure to which it is exposed. Type I baroreceptors would be more likely to reset in response to a sustained acute change in pressure, since their primary role would be to prevent the initial change in pressure. However, type II baroreceptors would not reset to the acute change in pressure, since their primary role would be to maintain consistent information on the level of existing pressure. Therefore, this study was performed to examine the acute resetting ability of both types of baroreceptors by using a vascularly isolated carotid sinus preparation in the dog.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Self-neglect in adult life.

Two cases of self-neglect in adult patients with no psychiatric diagnosis are reported. The presentation included domestic squalor and hoarding of rubbish, with the patients living alone and having a history of schizoid and paranoid personality traits. Both refused all recommended help. A move to more protected accommodation was the only practical measure that led to a degree of improvement.

Activities of Daily Living↗
PubMed1992

One hundred consecutive laparoscopic cholecystectomies performed in a rural hospital.

Laparoscopic cholecystectomy has quickly become the treatment of choice by most surgeons for the treatment of gallstone disease. The authors reviewed their first 100 consecutive patients undergoing laparoscopic cholecystectomy at a rural hospital. Twenty-three patients had previous abdominal procedures. The open insufflation technique was used on all patients with previous abdominal operations, with the exception of those who had an appendectomy only. Operative cholangiography was performed routinely and successfully on all patients, with the exception of the first seven because of nonavailability of a cholangiocath. In 54 percent of the first two-thirds of these patients, the operation was completed in less than 1.5 hours. In contrast, 88 percent of the last one-third of the patients were operated on within the same time period. All but 9 of the 100 patients were discharged within 24 hours of their surgery. Laparoscopic cholecystectomy can be performed safely and routinely in the rural hospital setting with results similar to those expected in larger metropolitan centers.

Cholangiography↗
PubMed1991

The effect of circulating antigen and radiolabel stability on the biodistribution of an indium labelled antibody.

This study has investigated two of the main problems with radiolabelled antibody imaging, the formation of circulating immune complexes (I.C.) and the non specific binding of radiolabel to the antibody molecule. Patients undergoing immunoscintigraphy with 111In labelled monoclonal antibody ICR2 were divided into three groups who received either the radiolabelled antibody alone (control, n = 12), the radiolabelled antibody which was incubated with the chelating agent diethylene triamine pentacetic acid (DTPA) prior to size exclusion chromatography (n = 6) or whose injectate was treated with DTPA and cold MAb administered intravenously prior to radiolabelled MAb administration (n = 6). Radiolabelled antibody uptake in abdominal organs was measured by region of interest analysis using a gamma camera with online computer and that in tumour and normal tissues by gamma well counting of biopsies. Circulating antigen and immune complex was measured by high pressure liquid chromatography (HPLC). The sensitivity of tumour imaging and the tumour uptake of radiolabelled antibody was not significantly different between the groups. Patients with high circulating antigen levels developed high levels of circulating immune complex but also had high tumour uptakes of radiolabelled antibody. Administration of cold MAb increased the splenic, but did not effect the tumour uptake of radiolabelled antibody and only minimally reduced levels of circulating immune complex. Chelate administration reduced the urinary excretion of radioactivity but increased the liver uptake of radioactivity. These results have shown that successful antibody imaging can be carried out despite high levels of circulating antigen, that large doses of unlabelled antibody are required to prevent immune complex formation and that removal of non specifically bound 111In does not reduce the liver uptake of radioactivity.

Aged↗
PubMed1991

Identification and map position of YAC clones comprising one-third of the Arabidopsis genome.

YAC clones corresponding to 125 Arabidopsis thaliana RFLP markers have been identified. At least one YAC clone has been isolated for each of the RFLP markers tested. Based on CHEF gel analysis of 196 clones, the mean insert size of the available Arabidopsis YAC libraries is approximately 160 kb. The YACs of known genetic map location encompass about 30% of the Arabidopsis genome. The results presented here represent a first step towards assembly of an overlapping YAC library of the A. thaliana genome.

Arabidopsis↗
PubMed1991

Gender, parity and the prevalence of minor affective disorder.

Data from a two-stage survey of the general population were used to test the proposition that the over-representation of minor affective disorders among women was restricted to those who had had children, independently of current involvement in childcare. Initial analyses supported this proposition strongly. Subsequent linear logistic analyses were largely in favour of an effect of marriage rather than of parity, but it remains possible that part of the gender differences in rates of depression arises because of the effect of parity in raising female prevalence. If substantiated, the parity effect could operate through social or biological mechanisms; although its nature is unclear, it merits further investigation.

Adult↗
PubMed1991

The Fregoli syndrome and puerperal psychosis.

Four cases of the Fregoli syndrome occurring in the setting of puerperal psychosis are described. They are discussed in relation to previously reported cases and it is proposed that the acute onset of the psychosis and ambivalence arising with childbirth are important factors in the pathogenesis.

Adult↗
PubMed1991

Development of an efficient transposon tagging system in Arabidopsis thaliana.

We are currently developing a transposon tagging system in Arabidopsis thaliana using the maize transposable elements Ac and Ds. In order to make the system as efficient as possible, four different antibiotic resistance markers have been tested for their usefulness in monitoring excision and reinsertion of transposons in the Arabidopsis genome. Owing to the low transposition frequency of wild-type Ac in Arabidopsis we have also tested a number of modifications to the Ac element. Deletion of the CpG-rich region in the transposase 5' untranslated leader was found to significantly increase the activity of Ac in Arabidopsis. In our first non-targeted tagging experiment, 200 individuals with an inherited transposed Ac element have been collected and their progeny are being screened in families of twelve for segregation of mutant phenotypes. A two-element system, using Ac and Ds, is also being developed and a way of stabilising the Ds-induced mutations by counter selecting plants carrying the transposase source is being investigated. The Agrobacterium T-DNA insertions carrying the different transposons are currently being mapped onto the Arabidopsis RFLP map. Inverse polymerase chain reaction (IPCR) is being used to generate flanking DNA probes, that will be used on the RFLP blots to map the T-DNA relative to the other known markers. Once the first few have been mapped the first targeted tagging experiment will be initiated.

Arabidopsis↗
PubMed1990

Home treatment for acute psychiatric illness.

OBJECTIVE: To determine the factors influencing the successful outcome of community treatment for severe acute psychiatric illnesses that are traditionally treated in hospital. DESIGN: All patients from a single electoral ward who were either admitted to hospital or treated at home over a two year period (1 October 1987 to 30 September 1989) were included in the study and their case notes audited. The second year of the study is reported. SETTING: Electoral ward of Sparkbrook, Birmingham. SUBJECTS: 99 Patients aged 16-65 with severe acute psychiatric illness. RESULTS: 65 Patients were managed by home treatment alone; 34 required admission to hospital. The location of treatment was significantly (all p less than 0.05) influenced by social characteristics of the patients (marital state, age (in men), ethnicity, and living alone) and by characteristics of the referral (occurring out of hours; assessment taking place at hospital or police station). DSM-III-R diagnosis was more weakly associated with outcome. Violence during the episode was significantly related to admission, although deliberate self harm was not. CONCLUSIONS: Home treatment is feasible for most patients with acute psychiatric illness. A 24 hour on call assessment service increases the likelihood of success because admission is determined more strongly by social characteristics of the patient and the referral than by illness factors. Admission will still be required for some patients. A locally based mental health resource centre, a 24 hour on call service, an open referral system, and an active follow up policy increase the effectiveness of a home treatment service.

Acute Disease↗
PubMed1990

Genes for two herbicide-inducible cytochromes P-450 from Streptomyces griseolus.

Streptomyces griseolus ATCC 11796 contains two inducible, herbicide-metabolizing cytochromes P-450 previously designated P-450SU1 and P-450SU2 (P-450CVA1 and P-450CVB1, respectively, using nomenclature of Nebert et al. [D. W. Nebert, M. Adesnik, M. J. Coon, R. W. Estabrook, F. J. Gonzalez, F. P. Guengerich, I. C. Gunsalus, E. F. Johnson, B. Kemper, W. Levin, I. R. Phillips, R. Sato, and M. R. Waterman, DNA 6:1-11, 1987]). Using antibodies directed against cytochrome P-450SU1, its N-terminal amino acid sequence, and amino acid composition, we cloned the suaC gene encoding cytochrome P-450SU1. Similar information about the cytochrome P-450SU2 protein confirmed that a gene cloned by cross-hybridization to the suaC gene was the subC gene encoding cytochrome P-450SU2. The suaC and subC genes were expressed in Escherichia coli, DNA for both genes was sequenced, and the deduced amino acid sequences were compared with that of the well-characterized cytochrome P-450CAM from Pseudomonas putida. Both cytochromes P-450SU1 and P-450SU2 contain several regions of strong similarity with the amino acid sequence of P-450CAM, primarily in regions of the protein responsible for attachment and coordination of the heme prosthetic group.

Amino Acid Sequence↗
PubMed1990

Firing characteristics of single-fiber carotid sinus baroreceptors.

This study examined firing patterns of single-fiber carotid baroreceptors in response to slow ramp increases in carotid sinus pressure (1-2 mm Hg/sec) in vascularly isolated carotid sinus preparations in thiopental-anesthetized dogs (25 mg/kg, plus 10 mg/kg/hr). Two general types of baroreceptor discharge patterns were obtained: 1) type I, a discontinuous, hyperbolic pattern characterized by a sudden onset of discharge at threshold pressure with a relatively high threshold frequency, which gradually increased to a higher saturation firing rate and 2) type II, a continuous, sigmoidal pattern characterized by a gradual increase in discharge above threshold pressure and a relatively low threshold frequency and saturation firing rate. Type II baroreceptor curves typically showed spontaneous discharge below threshold pressure and significantly lower sensitivities, threshold frequency, saturation firing rate, and threshold pressure than those of type I receptors. However, the saturation pressures and operating ranges of the type II receptors were greater than those of type I receptors, and the pressure at which type II receptors had their greatest sensitivity was greater than that for type I receptors. Type I baroreceptors generally had large myelinated afferent A fibers; type II baroreceptors generally had smaller A and unmyelinated C fibers, based on conduction velocities. The presence of spontaneous activity with type II baroreceptors, combined with significantly lower sensitivities and wider pressure operating ranges seen relative to type I baroreceptors, suggests that these receptors may primarily serve to provide information on tonic, or baseline, levels of arterial blood pressure to the central cardiovascular centers. The sudden onset of discharge, higher sensitivities, and narrower operating ranges of type I baroreceptors suggest that their primary role may be to provide information on dynamic, sudden changes in arterial pressure.

Afferent Pathways↗
PubMed1990

Experimental and modeling study of the excitability of carotid sinus baroreceptors.

In this study we examined the effects of blockade of a transient K+ current with 4-aminopyridine (4-AP) on the static stimulus-response relation of myelinated carotid sinus baroreceptors (n = 8), using a vascularly isolated sinus preparation in sodium thiopental-anesthetized dogs. In one class of baroreceptors (type I), which did not fire spontaneously below the pressure threshold (Pth), 4-AP (10(-5) to 10(-4) M) decreased Pth in a dose-dependent manner and transformed the stimulus-response relation from a discontinuous, hyperbolic shape to a sigmoidal, continuous curve. After exposure to 10(-4) M of 4-AP, baroreceptors were spontaneously active below Pth. These effects of 4-AP were more pronounced in baroreceptors with a high control Pth and were independent of enhanced neurotransmitter release or changes in carotid sinus distensibility. In contrast, 4-AP had relatively little effect on type II baroreceptors, which under control conditions are characterized by a continuous, sigmoidal stimulus-response curve. We believe that these effects of 4-AP on baroreceptor discharge were mediated by blockade of a transient K+ conductance that was present at the receptor spike-initiation zone. This hypothesis was examined using a mathematical model based on the Hodgkin-Huxley axon, but modified to include the transient K+ conductance. The modeling results showed that the minimum current necessary to elicit action potential firing is an extremely sensitive function of the magnitude of this K+ conductance, supporting our experimental results obtained with 4-AP. Our findings suggest that a transient K+ conductance might play a role in the determination of Pth and that differences between type I and II receptors could be the result of differences in the effectiveness of this conductance in controlling spike-initiation zone excitability.

4-Aminopyridine↗