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Biomedical subjects

C E Hyde

Publications and source records attributed to C E Hyde.

13 recordsLinked to original sources
PubMed2000

Regulation of the early expression of the Xenopus nodal-related 1 gene, Xnr1.

The Xenopus nodal related-1 (Xnr1) gene has a complex expression pattern in embryos, with two temporal phases. In the first phase, transcripts are first detected in perinuclear sites in the vegetal region of the blastula. During gastrulation, this expression disappears and transcripts become localised to the dorsal marginal zone. Expression stops and then restarts in a second phase at neurula and tailbud stages, firstly in two symmetric patches near the posterior end of the notochord, and then asymmetrically in a large domain in the left lateral plate mesoderm. In this study, we have investigated the regulation of the early phase of expression of Xnr1. We show that the T-box transcription factor VegT can induce Xnr1. It had previously been shown that Xnr1 can induce VegT in ectoderm cells and we show that the early expression of Xnr1 is regulated by an autoregulatory loop. By inspection of the Xnr1 promoter sequence, we have identified two non-palindromic T-box-binding sites, which are 10 bp apart. Using mutational analysis, we have shown that these elements are required for the VegT induction of Xnr1. The Xnr1 promoter shows striking homologies with the Xnr3 promoter. In particular, two elements that are required for Wnt signaling are conserved between these two promoters, but the two T-box sites are not conserved, and Xnr3 is not induced by VegT. A region of the promoter containing the T-box sites and the Wnt sites is sufficient to drive expression of a reporter gene in a dorsal domain in transgenic Xenopus at the gastrula stage. We show that this pattern of expression of the transgene in gastrulae is not dependent on the T-box sites.

Animals↗
PubMed1999

Expression pattern of a novel hyaluronidase during Xenopus embryogenesis.

We have isolated a cDNA encoding a novel hyaluronidase, which is expressed during embryogenesis. The encoded protein was expressed as a fusion polypeptide with glutathione S-transferase, and the affinity-purified fusion protein was shown to possess hyaluronidase activity with a pH optimum about pH 4.0. The expression of the XEH1 gene was analysed by in situ hybridization, and was first apparent in scattered cells in a broad ventral region of late gastrula embryos. As development proceeded through to tailbud stages, the domain of expression became progressively more restricted, eventually being located in the developing liver rudiment near the primary hepatic cavity. The results reveal the dynamic regulation of the contrasting activities of hyaluronan synthesis and degradation during early morphogenetic movements.

Amino Acid Sequence↗
PubMed1996

Psychiatric intensive care in acute psychosis.

We have reviewed the development of psychiatric intensive care, focusing on organizational factors and the causes of psychiatric violence, suggesting guidelines for rapid tranquillization. The economics of running a psychiatric intensive care unit were subjected to an analysis of fixed, semi-fixed and variable costs. Variable costs (treatment and patient numbers) were shown to be more open to manipulation and possible cost savings.

Acute Disease↗
PubMed1994

Similar properties of fetal and adult amine transporters in the rat brain.

A variety of drug classes, including psychomotor stimulants and antidepressants, interact with monoamine transporters in order to exert their effects. Although these transporters have been extensively characterized in the adult brain, little is known about uptake mechanisms in the fetal system. High affinity dopamine (DA) and serotonin (5-HT) uptake in the striatum and frontal cortex, respectively, were examined in rat fetuses (embryonic day 20; E-20). These results were then compared to uptake in adult rat synaptosomal preparations of the same regions. The data indicate that the fetal (E-20) uptake mechanism is sodium-dependent. Furthermore, the potency of various agents to inhibit transporter function was assessed. These drugs produced a concentration-dependent inhibition of uptake, and the resulting IC50 values were not significantly different from those obtained in the adult preparations. Our results provide evidence that the affinity of monoamine uptake inhibitors for fetal (E-20) DA and 5-HT transporters is similar to that observed with adult transporters. This observation has broad implications when considering neuronal development and in utero exposure to drugs that exert their effects through these transporters.

Aging↗
PubMed1993

Long-term cocaine administration is not neurotoxic to cultured fetal mesencephalic dopamine neurons.

The psychostimulants cocaine and methamphetamine produce their euphoric effects through an interaction with the mesolimbic dopamine system. Methamphetamine, unlike cocaine, has been shown to be neurotoxic to both dopaminergic and serotonergic systems. We have previously determined that a 6 day exposure to methamphetamine causes neuronal damage to tyrosine hydroxylase-immunopositive cells in our tissue culture model of the mesencephalon. Over the same exposure period, cocaine neither impaired neuronal function nor altered dopamine cell survival. To test whether a longer exposure period to cocaine would alter dopamine function, we added cocaine (100 microM) to the cultures once daily for either 8 or 11 days and examined changes in dopamine uptake, cell survival and morphology 24 h after the last administration. Cocaine did not produce any signs of neurotoxicity in the mesencephalic cultures.

Animals↗
PubMed1993

A "biofeedback" approach to the treatment of chronic polydipsia.

A novel behavioral method is described for the treatment of psychogenic polydipsia in a patient suffering from chronic schizophrenia. The patient was given feedback on serum sodium concentration, likely physical consequences, and the value of reducing fluid intake. An ABAB single-case design was used, with changes in sodium concentration (charted by the patient during the treatment phases) as the dependent variable. The patient showed substantially increased sodium concentration, which was maintained despite the withdrawal of feedback. This behavioral method appears promising in settings where restriction of fluid intake is not practical or ethical.

Adult↗
PubMed1993

Differing neurotoxic potencies of methamphetamine, mazindol, and cocaine in mesencephalic cultures.

The potent reinforcing effects of methamphetamine and cocaine are thought to be mediated by their interactions with CNS dopamine neurons. Both stimulants share the ability to block dopamine uptake potently, and methamphetamine can release cytoplasmic dopamine as well. There is also abundant evidence demonstrating the neurotoxic effects of methamphetamine. There are, however, limited studies that attempt to discern the neurotoxic mechanisms of these agents. The purpose of the present study was to characterize and compare the chronic in vitro effects of methamphetamine, cocaine, and the dopamine uptake blocker, mazindol, on cultured fetal mesencephalic dopamine neurons. Our studies examined biochemical mechanisms to evaluate the contribution of reuptake blockade versus release of dopamine. Using a dispersed cell preparation of fetal mesencephalon, cultures were treated for 5 days with the three uptake blockers. Dopamine function was assessed by measuring high-affinity [3H]dopamine uptake and by examining cultures for the presence of tyrosine hydroxylase-immunopositive neurons. Nonspecific neurotoxicity was assessed by staining for neuron-specific enolase and measuring lactate dehydrogenase activity. The results indicate that repeated administration of high concentrations of methamphetamine (10(-4) and 10(-3) M) caused a generalized neurotoxicity whereas the effects of 10(-5) M methamphetamine appeared to be specific to dopamine cells. Likewise, treatment of the cultures with mazindol (10(-6) M) resulted in reduced dopamine uptake while not significantly affecting neuron-specific enolase or tyrosine hydroxylase immunostaining. On the other hand, repeated exposure to cocaine (10(-5) and 10(-4) M) did not alter dopaminergic function in these cultures. The different mechanisms of action of these stimulants may explain the differences in neurotoxic potency of these compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Douglas House. Seven years' experience of a community hostel ward.

Of 24 residents of a ten-bed, community-based hostel ward suffering chronic psychiatric illness, nine have been resettled in the community, with four more expected to follow them. Five residents have made Douglas House their home but another six have manifested behavioural disturbance necessitating return to hospital wards. We found community discharge to be associated with illnesses having good prognostic features, while organic illness militated against such placement. Indicators of a prior history of behavioural disturbance seem to predict difficulties in managing a patient in this environment.

Activities of Daily Living↗
PubMed1991

'Ecstasy' psychosis and flashbacks.

We report three cases of flashbacks and one case of recurrent psychosis experienced by three MDMA users. We draw the attention of clinicians to the combination of adverse effects observed with this drug of abuse and to the advisability of prolonged treatment should they occur.

3,4-Methylenedioxyamphetamine↗
PubMed1989

The chronically mentally ill in community facilities. A study of quality of life.

The quality of life of chronically mentally ill patients in acute wards in a district general hospital, a hostel ward and group homes was compared. Within the spectrum of care of these patients, the severity of psychopathology corresponded to their placement. Analysis, including adjustments for the influence of psychopathology, showed differences between the three types of facility. Although differences existed between all types of care, residents in group homes and the hostel ward shared more similarities in quality of life than those in the district general hospital. Problems of caring for the chronically mentally ill on acute wards are highlighted.

Adult↗
PubMed1987

Electrodermal response as a monitor in electroconvulsive therapy.

A study comparing the use of electrodermal response with the cuff technique and clinical judgment as monitors in electroconvulsive therapy is reported. A sensitivity of 90.5% and a specificity of 41.7% were found and it is, therefore, suggested that this method is not used routinely.

Electroconvulsive Therapy↗
PubMed1979

The use of television in the assessment of home and foreign postgraduate groups during an introductory course in psychiatry.

Videotapes were developed for testing the ability to detect psychiatric phenomena, methods of questioning and interview technique. These were capable of discriminating between the performance of home graduates (HGs) and foreign graduates (FGs) and were consistent with other test results. These were significant differences between HGs and FGs on all tests before and after teaching. HGs started with high scores on all tests and these remained high, although no significant improvement occurred with teaching. FGs started with lower scores and showed improvement on the videotape test only, after teaching. HGs and FGs were exposed to video teaching methods but FGs rated video demonstration as a more helpful teaching mode.

Adult↗