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Biomedical subjects

A Richardson

Publications and source records attributed to A Richardson.

At least 235 records · Page 13Linked to original sources
PubMed1991

Macrophage-like cells originate from neuroepithelium in culture: characterization and properties of the macrophage-like cells.

Cultures of astroglia from C3H/HeJ mice, which are resistant to bacterial cell wall polysaccharide (LPS), initiated from embryos of Theiler stage 14 (9 days of gestation) up to Theiler stage 25 (17 days of gestation) as well as newborn animals, when subjected to nutritional deprivation, i.e. non-feeding of cultures, form large numbers of macrophage-like cells. These cells express Mac-1, Mac-3, F4/80 and Fc antigens. The cells are negative for GFAP, positive for vimentin, express Ia antigen and take up DiL-Ac-LDL. They are positive to non-specific esterase, secrete lysozyme and are phagocytic. Their morphology and ultrastructure closely resemble those of macrophages. Cultures initiated from neuroepithelium of Theiler stage 13 (8.5 days of gestation), before vascularization, when subjected to nutritional deprivation, also produce macrophage-like cells. Using spleen colony assay and methyl cellulose cultures, we were unable to detect the presence of hemopoietic (macrophage) precursor cells in astroglia cultures. This supports the hypothesis that the macrophage-like cells are of neuroectodermal origin and probably correspond to resident microglia of the CNS. Using nutritionally deprived astroglia cultures, a procedure was developed for isolation of macrophage-like cells and production of highly enriched macrophage-like (microglia) cultures.

Animals↗
PubMed1991

Spontaneous changes in the rotation of premolar teeth from eruption until the established dentition.

The aim of this study was to investigate whether the rotation of teeth changed from the point of eruption until the established dentition. The first 50 cases with adequate records enrolled in the Belfast Growth Study were selected, and the premolar rotation was measured at the point of eruption and again at age 15 in the established dentition. All premolars in a quadrant with early loss of the deciduous predecessors, early loss of the first permanent molars or absence of premolars, were disregarded. The results showed that the second premolars in both the upper and lower arches which erupted rotated had a tendency to improve over the observed period. Upper and lower first premolars which erupt rotated show the same tendency to improve, but to a lesser extent and less frequently than the second premolars. There seemed to be cases where a premolar deteriorated over the period, especially the first premolars.

Adolescent↗
PubMed1991

Theories of self-care: their relevance to chemotherapy-induced nausea and vomiting.

Nausea and vomiting are reputed to be two of the most disruptive side-effects associated with chemotherapy. Pharmacological and behavioural interventions are well described in the literature, but sparse attention appears to have been focused upon the role of self-care. This paper outlines the problem of chemotherapy-induced nausea and vomiting. The concept of self-care is described, including possible motivations to perform self-care, and potential relationships between symptom perception and self-care are noted. It concludes with suggestions for theoretical work and future research studies concerning self-care behaviour for nausea and vomiting induced by chemotherapy.

Antineoplastic Agents↗
PubMed1991

Short chain fatty acids in the terminal ileum accelerate stomach to caecum transit time in the rat.

We have previously shown that infusion of triglycerides and long chain fatty acids into the ileum of humans and rats delays small bowel transit time. The present studies have investigated the effect on the stomach to caecum transit time of a baked bean meal of the ileal infusion of 20 mM, 50 mM, and 100 mM acetic, butyric, hexenoic, and caprylic acids in rats. After an 18 hour fast either a control or a short chain fatty acid (SCFA) solution (pH 6.5) was infused into the ileum for 30 minutes (0.3 ml/hour). A test meal was given by gavage and the infusion continued for a further 150 minutes. The arrival of the meal in the colon was signalled by a rise in the exhaled hydrogen concentration. Acetic acid (20 mM, 50 mM, 100 mM), butyric acid (100 mM), and caprylic acid (100 mM) produced a significant acceleration of transit which was inversely proportional to SCFA chain length. In a separate experiment, infusion of 100 mM acetic acid, the most potent SCFA, into an isolated ileal Thirty-Vella loop failed to accelerate transit of the test meal. Our results suggest that SCFAs accelerate transit via a local enteric reflex.

Acetates↗
PubMed1991

Hepatic dystychoma: a five year experience.

In 5 years, 64 solid hepatic lesions have been referred for diagnosis and management which have been found unexpectedly on organ imaging in well patients. We have called this lesion a "dystychoma". Patients have undergone a two phase investigation programme which allows a diagnosis without admission to hospital in about 50% of cases. About three quarters of patients (47/64) have had non-neoplastic lesions, and about half (33/64) have had haemangiomas. About one patient in four (17/64) has had a neoplasm, and the neoplasm has been malignant in about one in six (11/64) of all patients. We stress the need to pursue the diagnosis in these patients. There were no reliable clinical, biochemical or imaging characteristics which individually distinguished benign from malignant lesions. Age over 55 years, an enlarged liver or a palpable liver mass and a raised serum alkaline phosphatase were all significantly more frequent with malignant tumours. The risk of malignancy rose with the number of risk factors, and all patients with all three risk factors had malignant tumours. Only 11 of the 64 patients were judged to have benefited by significant increase in quality or quantity of life as a result of what was frequently inappropriate organ imaging. There is no strong argument for replacing history taking and physical examination by CT scanning, ultrasound examination or other organ imaging.

Adolescent↗
PubMed1991

Lifestyle changes in mild asthma during intermittent symptom-related use of terbutaline inhaled via 'Turbohaler'.

Beta 2-agonist therapy effectively relieves asthmatic symptoms, but an improvement in patient lifestyle has not been demonstrated. This open study in which patients acted as their own controls, assessed the efficacy and acceptability of intermittent symptom-related use of terbutaline inhaled via 'Turbohaler', and its influence on the lifestyle of 1133 inhaler-naive, mild asthmatics treated in general practice. A 1-week run-in period was followed by 4-weeks' treatment with inhaled terbutaline (500 micrograms as required). Peak expiratory flow rate (PEFR) and 'Turbohaler' technique were assessed at clinic visits. Diary cards, completed daily, assessed: the number of terbutaline inhalations, the relief obtained after use, the severity of asthma symptoms (cough, morning wheeze, nocturnal wheeze and wheeze on activity), and lifestyle indices (sleep disturbance, work/school days lost, limitation of normal activity). After terbutaline treatment, PEFR increased by 54 +/- 2 l/min (p less than 0.001), the severity of asthma symptoms was almost halved (p less than 0.001), with over two-thirds (65% to 76%) of patients reporting improvements in each variable, and the adverse effect of asthma on lifestyle was at least halved (p less than 0.001). Improvements in lung function, asthma symptoms and lifestyle were comparable for all sub-groups: adults (greater than 16 years), school-age children (6 to 16 years) and preschool children (less than or equal to 5 years). This study not only confirmed the efficacy and acceptability of intermittent symptom-related use of terbutaline inhaled via 'Turbohaler', but also demonstrated that its use enhanced patients' lifestyles.

Activities of Daily Living↗
PubMed1990

The expression of granulocyte/macrophage colony-stimulating factor in activated mouse lymphocytes declines with age.

The expression of granulocyte/macrophage colony-stimulating factor (GM-CSF) was studied in spleen lymphocytes isolated from male C57BL/6J mice of 6, 20, and 29 months of age. GM-CSF expression (biological activity and mRNA level) was maximum after culturing the lymphocytes for 45 hr with concanavalin A and phorbol myristate acetate. The induction of both GM-CSF activity and mRNA levels was observed to decline over 60% between 6 and 29 months of age. The age-related decline in the level of GM-CSF paralleled the age-related decline in the mRNA levels of interleukin-2 and interleukin-3.

Aging↗
PubMed1990

GABA receptor modulation of tyrosine hydroxylase gene expression in the rat adrenal gland.

Chromaffin cell gamma-aminobutyric acid (GABA) receptors play a role in modulating catecholamine secretion. The present experiments examined the role of GABA receptors in modulation of tyrosine hydroxylase (TH) induction in rat adrenal gland. Administration of bicuculline, a GABA antagonist, had no effect on TH activity or TH mRNA. However, bicuculline potentiated reserpine's effect on TH activity and TH mRNA induction. These data suggest that GABA receptors modulate induction of TH and TH mRNA in the adrenal gland.

Adrenal Glands↗
PubMed1990

Modulation of tyrosine hydroxylase gene expression in the rat adrenal gland by age and reserpine.

Tyrosine hydroxylase (TH), TH messenger RNA (TH mRNA) and dopamine (DA) were measured simultaneously in adrenal glands of individual Fischer 344 rats aged 2, 6, 13 and 23 months. Between 2 and 23 months TH activity rose 2-fold as compared to the youngest group. TH mRNA content of the adrenal gland rose 3-fold between 2 and 23 months. A 3-fold increase in adrenal DA content, the first catecholamine product of TH, provides evidence that the increases in TH gene expression are functionally significant. To determine if mechanisms that regulate gene expression are altered by aging, the effects of reserpine on induction of TH mRNA and TH activity were compared in another group of rats aged 2, 12 and 27 months. Consistent with the results of the first experiment, there were age-related increases in both TH activity and TH mRNA in the age-matched control groups. TH activity rose 2-fold and TH mRNA rose more than 6-fold between 2 and 27 months. The discrepancy in the relative magnitudes of increases in TH mRNA and TH protein suggest an uncoupling of regulation of TH mRNA and TH protein levels. Moreover, there were significant age-related differences with respect to modulation of TH gene expression by reserpine treatment. TH activity was induced by reserpine in the youngest group, but not in the two older age-groups. In contrast, reserpine caused significant induction of TH mRNA in all age groups. These results provide evidence that aging is accompanied by alterations in transcriptional and post-transcriptional mechanisms involved in regulation of TH gene expression.

Adrenal Glands↗
PubMed1990

Undergraduate orthodontics--a collision course on occlusion.

Five years ago the dental school at Belfast instituted a 'longitudinal course' in orthodontics. It has meant changes to attitudes and working practices, and staff and students have been both flexible and open minded. Here, Andrew Richardson and Hill Mercer, outline the course, the contortions, and some of the problems that have been straightened out.

Curriculum↗
PubMed1990

Factors likely to affect participation in mammographic screening.

A survey of 290 women likely to be eligible for mammographic screening was carried out to identify the characteristics of a screening programme, and of women, that could affect participation. Aspects of the service that are likely to increase participation include a screening centre within 30 minutes travel by car (only 28% of women surveyed thought more than 30 minutes travel time was reasonable), appointment times outside normal working hours (17% of women surveyed), female staff (35% of respondents would prefer female staff), and publicity before invitations are sent out. Eighty-four percent of all women surveyed intend to participate in screening; intended participation was higher among women under 50, women whose knowledge about breast cancer and mammographic screening was good, and women who have regular cervical smears and dental checks.

Adult↗
PubMed1990

Effect of age on the expression of antioxidant enzymes in male Fischer F344 rats.

Age-related changes in the activities of superoxide dismutase, catalase, and glutathione peroxidase were determined in brain, heart, hepatocytes, intestinal mucosa, and kidney from male Fischer F344 rats. Superoxide dismutase activity decreased significantly with age in all five tissues studied. The activity of catalase decreased with age in brain, hepatocytes, and kidney while glutathione peroxidase activity decreased significantly with age only in intestinal mucosa and kidney. The relative levels of superoxide dismutase, catalase, and glutathione peroxidase mRNA were measured in brain, hepatocytes, and kidney. An age-related decrease in SOD and catalase mRNA was observed for brain, hepatocytes, and kidney. GPX mRNA levels decreased with age in hepatocytes and kidney but did not change with age in brain. In general, the age-related changes in the activities of SOD, catalase, and GPX were paralleled by a similar change in the relative level of the mRNAs coding for these enzymes.

Aging↗
PubMed1990

Food restriction retards age-related histological changes in rat small intestine.

Previous studies have reported that small and large intestinal crypt hyperplasia and hyperproliferation occur in senescent rats about 27 mo of age. We have studied duodenal and ileal architecture in ad libitum chow-fed rats and have demonstrated that the increase in duodenal crypt depth and crypt hyperplasia do not develop throughout the life span, but become apparent at 21 and 27 mo of age. These crypt hyperplastic features occur without a change in duodenal villus cell number. Ileal villus cellularity increased throughout the life span, suggesting exposure to a gradually increasing luminal nutrient load. Diet restriction to 60% of the ad libitum feeding rate prolonged the life span of animals from 27 to greater than 33 mo and prevented both the duodenal hyperplasia and the increase in ileal villus cell numbers to the age of 27 mo. Thirty-three-month diet-restricted rats did show evidence of duodenal crypt hyperplasia. We conclude that proximal intestinal hyperplasia is a phenomenon that develops in advanced age, but that ileal villus cellularity increases throughout the ad libitum-fed rodent life span. Diet restriction dramatically retards these intestinal changes that are seen with ad libitum feeding and provides an experimental model for the study of age-related cellular changes of the rodent gastrointestinal tract.

Aging↗
PubMed1990

The effect of ethanol on the normal food intake and eating behaviour of the rat.

A computerised system was used to continually monitor the food intake and meal patterns of six rats over eighteen days. The effect of replacing the normal drinking water with a 10% ethanol solution for the second six-day period was assessed. Fluid intake decreased by 29% and resulted in a mean ethanol consumption of 6 ml/kg/rat/day. Energy intake remained unchanged with food intake being significantly reduced (p less than 0.05) in proportion to the calories consumed as ethanol. The reduction in food intake was achieved by a significant decrease in mean meal size (p less than 0.01), whilst meal frequency demonstrated a nonsignificant increase. Withdrawal of the ethanol solution resulted in highly variable feeding behaviour. It is concluded that rats will adapt their meal patterns to regulate their energy intake when a 10% ethanol solution is the sole fluid source. It is suggested that the caloric potential of ethanol is recognised through the release of CCK and consequently meal pattern adaptations are the result of premature satiety.

Alcohol Drinking↗
PubMed1990

Effect of dietary restriction on the age-dependent changes in the expression of antioxidant enzymes in rat liver.

The effects of aging and dietary restriction on the expression of several enzymes (superoxide dismutase, catalase and glutathione peroxidase) that are involved in free radical detoxification were studied in liver tissue from male Fischer F344 rats. The expression (i.e., activities and mRNA levels) of superoxide dismutase (Cu-Zn) and catalase decreased with age in liver. Dietary restriction (40% restriction of energy intake) increased the activities of superoxide dismutase (24 to 38%) and catalase (64 to 75%) in liver at 21 and 28 mo of age. Glutathione peroxidase activity in liver of diet-restricted rats was significantly higher (37%) at 28 mo of age than that of rats fed ad libitum. The age-related changes in the relative levels of mRNA for superoxide dismutase, catalase and glutathione peroxidase paralleled the changes in the activities of these enzymes in rats fed ad libitum or rats fed the restricted diet. Thus, the changes in the activities of superoxide dismutase, catalase and glutathione peroxidase with age and dietary restriction appear to arise from changes in the levels of mRNAs coding for these enzymes. Free radical damage, as measured by thiobarbituric acid-reactive material and lipofuscin accumulation, was lower in diet-restricted rats than in rats fed ad libitum.

Aging↗
PubMed1990

The effects of photic stimulation and private self-consciousness on the complexity of visual imagination imagery.

Three levels of photic stimulation (6, 10, 18 Hz) were employed to induce visual imagination imagery in 40 female undergraduates, half of whom had been selected because they had an habitual interest in their own internal states and half because they had no such interest (high and low on a Private Self-conscious (PSC) scale). It was predicted, and found, that more complex images would be reported (1) under the averaged 6 and 10 Hz condition than under the 18 Hz condition, (2) under the 6 than under the 10 Hz condition, and (3) under the high PSC than under the low PSC condition. An interaction effect was also obtained such that the complexity of visual imagination imagery was greatest for the high PSC group, compared with the low PSC group, under the 6 Hz condition and least under the 18 Hz condition. Additional analyses were undertaken on the types of colour, form and movement reported by the high and low PSC groups under combined conditions of photic stimulation. The results of the complexity scores were discussed in terms of West's (1962) 'perceptual release' theory and several suggestions were made for future research.

Adolescent↗