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Biomedical subjects

G Halliday

Publications and source records attributed to G Halliday.

32 records · Page 2Linked to original sources
PubMed1995

Training to administer electroconvulsive therapy: a survey of attitudes and experiences.

Recent Royal Australian and New Zealand College of Psychiatrists guidelines regarding Electroconvulsive Therapy (ECT) call for "specific training in both the practical and theoretical aspects of ECT", involving provision of an "educational programme" by centres where ECT is administered, and "supervised administration of ECT prior to administering this treatment alone". This survey was undertaken to elicit the attitudes and experiences of current trainees in relation to training to administer ECT. It was found that ECT is given entirely by the registrars, that consultants are rarely or never present, and in most centres, training typically consists of registrars being supervised once or twice by another registrar, and thereafter administering ECT alone. Twenty percent of those who had given ECT, however, reported not being supervised the first time they administered it. Most trainees indicated limited theoretical teaching in this area, and almost none were aware of a formal training scheme at their respective hospitals. The College guidelines, as stated, address these issues, and priority should be given to their implementation.

Attitude of Health Personnel↗
PubMed1994

Analysis of staining methods for different cortical plaques in Alzheimer's disease.

This study evaluated current methods for demonstrating and categorizing cortical plaques, with the aim of establishing objective methodology for future diagnostic evaluation. Analysis of four methods of tissue processing revealed that the highest numbers of plaques were identified in formalin-fixed, paraffin-embedded tissue regardless of the stain used. Analysis of three silver stains and four immunohistochemical dilutions of an antibody to beta A4 protein revealed that the recent silver method published by Garvey et al. [(1990) J Histotechnol 14: 39-42] was equivalent to beta A4 immunohistochemistry in demonstrating the highest number of plaques. Plaque differentiation was easier and more reliable in silver compared to beta A4-stained sections, although the number of identifiable small compact plaques was significantly reduced in silver-stained sections. These studies show that plaque differentiation may be compromised by tissue processing and staining protocols. The establishment of superior methods may provide better diagnostic resolution for patients with Alzheimer's disease.

Aged↗
PubMed1994

Neuropathological correlates of memory dysfunction in the Wernicke-Korsakoff syndrome.

The Wernicke-Korsakoff syndrome is a neuropathological term which encompasses two clinical syndromes in thiamine-deficient alcoholics, Wernicke's encephalopathy and Korsakoff's psychosis. Wernicke's encephalopathy is characterised by eye and gait disorders and mental confusion, and can lead to the profound and permanent amnesia known as Korsakoff's psychosis. Despite this specific difference, both conditions appear to have identical neuropathology with haemorrhages and other lesions around the ventricular system. The memory deficit has been attributed to a number of brain lesions, including a recent suggestion that brain pathways utilising particular neurotransmitters are specifically damaged. To examine this, the number of chemically identified neurons in particular brain regions was quantified in patients with Wernicke's encephalopathy alone or in combination with Korsakoff's psychosis and compared with age- and sex-matched controls. Noradrenaline, a neurotransmitter thought to be involved in the process of selective attention, is localised in pathways projecting to the cortex. Our patients with either Wernicke's encephalopathy or additional Korsakoff's psychosis do not differ from controls in the distribution and number of these cells. Serotonin is another neurotransmitter that has been linked with alcohol dependency. Both patient groups have a profound loss of serotonin-containing neurons compared with controls. The loss of forebrain neurons containing acetylcholine in patients with Alzheimer's disease has implicated this neurotransmitter in the maintenance of memory functions. There was a large variation in the number of these forebrain neurons in thiamine-deficient alcoholics compared with controls. Cholinergic cell loss reflected the severity of cognitive dysfunction, but was not exclusive to patients with amnesia. Two thalamic nuclei are involved in relaying memories for storage and retrieval, the anterior and mediodorsal thalamic nuclei. While patients with Wernicke's encephalopathy often had neuronal loss in the mediodorsal nucleus, only patients with Korsakoff's psychosis had cell loss in both medial thalamic nuclei. The results suggest that cumulative lesions contribute to the amnesia seen in thiamine-deficient alcoholics, including deficits in serotonergic, cholinergic and medial thalamic pathways.

Acetylcholine↗
PubMed1993

Thalamic vacuolation in acute Wernicke's encephalopathy [corrected].

Two patients with acute Wernicke's encephalopathy, with the diagnosis confirmed pathologically at autopsy, showed substantial vacuolation and neuronal degeneration in discrete nuclei of the thalamus. Thalamic vacuolation has not been described previously in acute Wernicke's encephalopathy. The use of frozen sections to minimize processing artifact was fundamental in demonstrating this pathology. The pathogenic mechanism underlying this change appears to be different to that seen in the more typical periventricular, mamillary body and brainstem lesions. We hypothesize that a specific neural pathway may be involved and suggest that this pathway could be the ascending nitric oxide-containing cholinergic pathway from the brainstem.

Adult↗
PubMed1993

Brainstem serotonergic neurons in chronic alcoholics with and without the memory impairment of Korsakoff's psychosis.

There are several lines of evidence to suggest that serotonergic neurons in the brain are detrimentally affected by chronic alcohol consumption. The present study aims to quantify pathological changes in brainstem regions containing serotonergic neurons in chronic alcoholics compared to age-matched non-alcoholic controls. An antibody specific for tryptophan hydroxylase was used to immunohistochemically demonstrate serotonergic neurons in serial sections of postmortem brainstem. The cases analyzed were divided into four groups on the basis of their clinical and pathological presentation; chronic alcoholics with Wernicke's encephalopathy, chronic alcoholics with additional Korsakoff's psychosis, non-alcoholic controls, and a single chronic alcoholic without neurological complications. There was an overall reduction in the number of serotonergic neurons in all alcoholic cases when compared with controls. All brainstem regions were affected, but the largest neuronal loss was found in areas of the medullary and caudal pontine reticular formation (reduced by 80-90%). Alcoholics with Korsakoff's psychosis did not differ in the amount or extent of pathology from the other alcoholic cases analyzed. The data indicate that significant numbers of serotonergic neurons degenerate in chronic alcoholics. Such a loss is likely to have significant clinical consequences.

Adult↗
PubMed1992

The locus coeruleus and memory: a study of chronic alcoholics with and without the memory impairment of Korsakoff's psychosis.

The loss of noradrenergic locus coeruleus neurons has been identified as the possible critical lesion inducing amnesia in alcoholic patients with the Wernicke-Korsakoff syndrome. The present study aims to test this hypothesis by quantifying the number of pigmented locus coeruleus neurons in 4 alcoholics with the Wernicke-Korsakoff syndrome, 5 alcoholics with Wernicke's encephalopathy alone but no amnesia, and 1 alcoholic and 5 age-matched controls with no neurological disorders. Apart from an increased vascularity in the locus coeruleus of alcoholics, no significant differences in the number, morphology or distribution of pigmented locus coeruleus neurons was noted between any of the groups analysed. There was a significant correlation between the number of locus coeruleus neurons and brain weight. These data demonstrate that neither alcohol neurotoxicity nor thiamine deficiency result in a reduction in the number of pigmented cells in the locus coeruleus and refute the hypothesis that locus coeruleus cell loss is critical for the amnesia in the Wernicke-Korsakoff syndrome.

Adult↗
PubMed1992

Preliminary evidence suggesting delayed development in the hypoglossal and vagal nuclei of SIDS infants: a necropsy study.

Little neuropathology has been documented in sudden infant death syndrome (SIDS) infants. Two hypotheses predict abnormalities in the hypoglossal nucleus and dorsal motor nucleus of the vagus: first, that upper airways are obstructed as a result of abnormal innervation (principally the hypoglossal nerve), and second, that they are obstructed as a result of abnormal cardiorespiratory control (the vagus nerve). A quantitative morphometric analysis was carried out to test these hypotheses in SIDS infants and controls (who died in accidents). The following nuclei dimensions were analyzed; length, volume, density, and estimated total cell number. In addition, cell size was analyzed. There were no differences in the anatomical distribution, site, or number of neurons between the groups. The most significant difference between the SIDS and control infants was the neuronal size: control infants had significantly larger neurons. In many other variables, there were trends suggesting a difference between the groups: the volume occupied by the neuronal populations was smaller in the SIDS infants, and therefore the neuronal density was increased. These values suggest differences in the development of these nuclei between SIDS and control infants.

Autopsy↗
PubMed1992

A comparative study of avidin-biotin-peroxidase complexes for the immunohistochemical detection of antigens in neural tissue.

It has been suggested that the use of avidin-biotin immunohistochemical techniques for antigen detection in neural tissue produces nonspecific background staining. For this reason neural tissue was used to test the quality, sensitivity and specificity of four commercially available antibody detection kits which use avidin or streptavidin binding to biotin. Free-floating, thick-section immunohistochemistry on perfusion fixed rat central nervous system revealed variability among staining kits for all parameters analyzed under the same experimental conditions. The reagents from the Vector 'Elite' kit were the most sensitive and specific, and received the highest overall rating for quality. Most commercial products tested could be used at greater dilutions than those recommended by the manufacturers without compromising specific staining. No staining was evident when the primary and secondary antibodies were omitted. This suggests that nonspecific binding is unlikely to be due to endogenous ligands, charge or hydrophilic reactions between these tertiary complexes and the tissue sections.

Animals↗
PubMed1988

Substance P-like immunoreactive fibres in the ventromedial mesencephalic tegmentum of rat.

The distribution and morphology of the substance P-like immunoreactive (SP-IR) fibres and terminals in the rat ventromedial mesencephalic tegmentum (VMT) were studied using qualitative and quantitative immunohistochemical methods at light and electron microscopic levels. All five component nuclei of the VMT were examined and the size, number and density of immunoreactive terminals determined. The SP-IR fibres were distributed heterogeneously within the VMT. Under the electron microscope, SP-IR axon terminals contained both clear and dense-cored vesicles and made both symmetrical and asymmetrical synapses. The ultrastructure of the SP-IR terminals appeared to differ between nuclei. Small, clear vesicle terminals made symmetrical synaptic junctions with small calibre dendrites in the paranigral nucleus while large, clear and dense-cored vesicle terminals made asymmetrical junctions with somata and large calibre dendrites in the interfascicular nucleus. Quantitative differences between the VMT nuclei were also seen in the density of SP-IR terminals, the paranigral nucleus contained the highest density and the rostral linear nucleus the lowest. A comparison between the number of SP-IR terminals and the total number of axon terminals in the VMT reveals that the majority of all terminals in the paranigral nucleus were SP-IR, as well as the majority of axosomatic synapses in the interfascicular nucleus. These regional differences in the SP-IR innervation suggest that substance P and related peptides may perform several specific functions within the VMT and therefore have a more variable influence on this region than was previously thought.

Animals↗
PubMed1982

Direct alteration of a traumatic nightmare.

A brief case history of a young male farm worker who suffered recurrent nightmares subsequent to being run over by a tractor is given. A method for reducing the nightmares, by encouraging the patient to alter a small, emotionally nonsignificant detail of the dream, is then described.

Adult↗
PubMedDate not supplied

Alzheimer's disease and inflammation: a review of cellular and therapeutic mechanisms.

1. Of the neurodegenerative diseases that cause dementia, Alzheimer's disease (AD) is the most common. Three major pathologies characterize the disease: senile plaques, neurofibrillary tangles and inflammation. We review the literature on events contributing to the inflammation and the treatments thought to target this pathology. 2. The senile plaques of AD consist primarily of complexes of the beta-amyloid protein. This protein is central to the pathogenesis of the disease. 3. Inflammatory microglia are consistently associated with senile plaques in AD, although the classic inflammatory response (immunoglobulin and leucocyte infiltration) is absent. beta-Amyloid fragments appear to mediate such inflammatory mechanisms by activating the complement pathway in a similar fashion to immunoglobulin. 4. Epidemiological studies have identified a reduced risk of AD in patients with arthritis and in leprosy patients treated with anti-inflammatory drugs. Longitudinal studies have shown that the consumption of anti-inflammatory medications reduces the risk of AD only in younger patients (< 75 years). 5. There is a considerable body of in vitro evidence indicating that the inflammatory response of microglial cells is reduced by non-steroidal anti-inflammatory drugs (NSAID). However, no published data are available concerning the effects of these medications on brain pathology in AD. 6. Cyclo-oxygenase 2 enzyme is constitutively expressed in neurons and is up-regulated in degenerative brain regions in AD. Non-steroidal anti-inflammatory drugs may reduce this expression. 7. Platelets are a source of beta-amyloid and increased platelet activation and increased circulating beta-amyloid have been identified in AD. Anti-platelet medication (including NSAID) would prevent such activation and its potentially harmful consequences. 8. Increased levels of luminal beta-amyloid permeabilizes the blood-brain barrier (BBB) and increases vasoconstriction of arterial vessels, paralleling the alterations observed with infection and inflammation. Cerebral amyloidosis is highly prevalent in AD, compromising the BBB and vasoactivity. Anti-inflammatory medications may alleviate these problems.

Aged↗