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Biomedical subjects

I Perry

Publications and source records attributed to I Perry.

16 recordsLinked to original sources
PubMed1999

Magnesium in drinking water supplies and mortality from acute myocardial infarction in north west England.

OBJECTIVES: To examine whether higher concentrations of magnesium in drinking water supplies are associated with lower mortality from acute myocardial infarction at a small area geographical level; to examine if the association is modified by age, sex, and socioeconomic deprivation. DESIGN: Small area geographical study using 13,794 census enumeration districts. Water constituent concentrations (magnesium, calcium, fluoride, lead) measured at water supply zone and assigned to enumeration districts. SETTING: 305 water supply zones in north west England. SUBJECTS: Resident population of 1,124,623 men and 1,372,036 women (1991 census) aged 45 years or more. MAIN OUTCOME MEASURE: Mortality from acute myocardial infarction, International Classification of Diseases, ninth revision (ICD-9) 410. Subsidiary analysis examined deaths from ischaemic heart disease, ICD 410-414. RESULTS: There were 21,339 male and 17,883 female deaths from acute myocardial infarction in 1990-92. Drinking water magnesium concentrations in water zones ranged from 2 mg/l to 111 mg/l (mean (SD) 19 (20) mg/l, median 12 mg/l); 24% of variation in magnesium concentrations was within zone and 76% was between zone. The relative risk of mortality from acute myocardial infarction (standardised for age, sex, and Carstairs deprivation quintile) for a quadrupling of magnesium concentrations in drinking water (for example, 20 mg/l v 5 mg/l) was 1.01 (95% confidence interval (CI) 0.99 to 1.03). When adjusted for north-south and east-west trends in mortality from acute myocardial infarction and for drinking water calcium, fluoride, and lead concentrations, this relative risk was 1.01 (95% CI 0.96 to 1.06). There was no evidence of a protective effect for acute myocardial infarction even among age, sex, and deprivation groups that were likely to be relatively magnesium deficient. For ischaemic heart disease mortality there was an apparent protective effect of magnesium and calcium (with calcium predominating in the joint model), but these were no longer significant when the geographical trends were incorporated. CONCLUSIONS: No evidence was found of an association between magnesium concentrations in drinking water supplies and mortality from acute myocardial infarction. These results do not support the hypothesis that magnesium is the key water factor in relation to mortality from heart disease.

Age Factors↗
PubMed1998

The right to die: a case for reform.

The debate over patients' right to die is a complex one. Here one nurse looks at the statutory requirements and ethical considerations and makes a case for the development of living wills.

Ethics, Medical↗
PubMed1995

Exercise ECG's.

Explore the source record for details and available documents.

Aerospace Medicine↗
PubMed1994

[Pulmonary embolism despite inferior vena cava filter].

The Greenfield filter is an effective and safe means of preventing postoperative pulmonary embolism in high-risk patients. However, it does not give absolute protection. We report a 69-year-old man who presented with deep vein thrombosis. Medical work-up revealed pancreatic tumor (Trousseau's sign). The Greenfield filter was placed in the inferior vena cava before operation. 11 days after total pancreatectomy clinical signs of pulmonary embolism appeared and the diagnosis was confirmed by ventilation-perfusion scan; anticoagulant therapy was instituted. The incidence of pulmonary embolism following interruption of the inferior vena cava by introducing the Greenfield filter is low (2.2%). Nevertheless, the diagnosis of pulmonary embolism should be considered in any patient with appropriate clinical signs, regardless of whether a filter was inserted.

Aged↗
PubMed1994

Maternal factors and development of cardiovascular risk: evidence from a study of blood pressure in children.

It has been suggested that risks of hypertension and cardiovascular disease begin in utero and that maternal nutrition plays an important role. We have examined the relation between maternal factors and BP in a study of 1,311 children in which physical measurements at 9-11 years of age have been linked to a parental questionnaire; birth record data were also available in a subsample of 662 children. Maternal height was inversely related to childhood BP after adjustment for the child's current height. However, several social factors related to maternal nutrition in pregnancy in earlier studies (including social class, housing tenure, maternal educational attainment and maternal smoking in pregnancy) showed weak and inconsistent relations with BP at 9-11 years. Minimum maternal haemoglobin in pregnancy and change in mean corpuscular volume in pregnancy (identified as potentially important markers of maternal nutrition in earlier studies) showed no consistent relationships either with placental weight to birthweight ratio or with childhood BP, although both factors showed strong inverse associations with birthweight. The association between maternal height and childhood BP may reflect the influence of early life factors on cardiovascular risk. However, the absence of consistent relationships between social factors and BP in offspring provides little support for the possibility that maternal diet is an important influence on cardiovascular risk factors in childhood. Minimum maternal haemoglobin and change in maternal mean corpuscular volume are unlikely to be specific markers of maternal nutrition in pregnancy. More specific hypotheses relating maternal nutrition to the development of cardiovascular risk in offspring are required.

Adult↗
PubMed1993

A simplified method for culture of endothelial cells and analysis of adhesion of blood cells under conditions of flow.

We have developed a simplified technique for culturing human umbilical vein endothelial cells under shear flow conditions, using prefabricated glass microcapillary tubes ("microslides") with a well-defined rectangular cross section and good optical quality. These microslides have been incorporated into a controlled flow system for quantitative video-microscopic analysis of the adhesion of blood cells to endothelial cells. Microslides were pretreated with 3-aminopropyltriethoxy-silane, or gelatin, and then loaded with a suspension of endothelial cells. After the cells had settled and attached to the substrate, the microslides were inserted into a flow-based culture system. Medium was drawn through them at intervals or continuously until confluency was reached (approximately 24 hr). Cells were cultured at wall shear stresses over a range 0.06 to 2.2 Pa. For adhesion assays, the endothelialized microslides were attached to microscope slides, and suspensions of blood cells were drawn through at desired wall shear stresses (0.02-0.5 Pa). Adhesion of malarial-infected red blood cells and of neutrophilic granulocytes was quantitated by direct microscopic observation. The adhesive behavior of both cell types closely resembled that previously described by ourselves and others using flow chambers incorporating endothelial-coated glass coverslips. The use of microslides represents a significant simplification of methodology for endothelial cell growth and adhesion studies under flow conditions.

Blood Cells↗
PubMed1993

Effect of activation on adhesion of flowing neutrophils to cultured endothelium: time course and inhibition by a calcium channel blocker (nitrendipine).

1. Adhesion of neutrophils to vascular endothelium plays an important role in inflammation and thrombosis. Modulation of adhesion may be therapeutic in these conditions. 2. A flow model was used to quantify adhesion of neutrophils to human cultured umbilical vein endothelial cells. The time course of the neutrophil response to activation by N-formyl-methionyl-leucylphenylalanine (fMLP, 10(-7) M) was studied and the inhibitory effects of the calcium-channel blockers, nitrendipine and nifedipine, were investigated. 3. Neutrophils adhered firmly to the endothelial cells without rolling, but initial attachment was highly dependent on shear stress; doubling the stress from 0.05 to 0.1Pa decreased the number of neutrophils adhering by over 80%. 4. Adhesion rapidly increased after activation of neutrophils by fMLP, peaking at 1-3 min post-treatment, and then decreased over the next 10-12 min. A monoclonal antibody to the beta 2-integrin component CD18 inhibited adhesion by over 80% for activated or unactivated cells. 5. The Ca-channel blocker, nitrendipine, but not nifedipine, significantly inhibited the fMLP-induced increase of adhesion in a dose-dependent manner (10(-8) to 10(-6) M). Dihydropyridines may be useful agents for modifying neutrophil function.

Adult↗
PubMed1990

Hyperthyroidism, inappropriate plasma TSH and pituitary adenoma in three patients, two receiving long-term phenothiazine therapy.

Hypersecretion of TSH by a pituitary adenoma is thought to be a rare form of hyperthyroidism. We describe three such patients, each of whom presented with clinical hyperthyroidism and a diffuse goitre, without eye signs or dermatopathy. Two were receiving long-term phenothiazine, one of these was also acromegalic. Plasma thyroxine, free T4 and tri-iodothyronine were repeatedly raised in each; plasma TSH was grossly elevated in one and inappropriately normal in the other two. Plasma TSH did not rise in response to thyrotrophin-releasing hormone or metoclopramide and was not suppressed by L-dopa in any patient. Anti-thyrotrophin receptor antibodies were undetectable. Skull radiographs showed erosion and expansion of the pituitary fossa and CT scans confirmed a pituitary mass in each patient. A pituitary adenoma was removed by transphenoidal surgery in two patients and a TSH-secreting adenoma was confirmed by immunocytochemical staining and electron microscopy. Both patients were clinically euthyroid post-operatively but still had evidence of TSH excess. Pituitary surgery was technically unsuccessful in the third patient. Although two patients had hyperthyroidism of long duration, all three were diagnosed within one year of the introduction of a sensitive TSH assay to our laboratory. A TSH-secreting pituitary adenoma may be a more common cause of hyperthyroidism than has been believed.

Adenoma↗
PubMed1989

Fulminant severe retinopathy in a newly diagnosed diabetic without risk factors.

The authors describe a 26-year-old female developing severe proliferative retinopathy within 2 weeks of diagnosis of insulin-dependent diabetes mellitus. The patient presented with profound diabetic ketoacidosis, but had no other risk factors for retinopathy. She had marked bilateral myopia which did not protect her from retinopathy. Nine months after diagnosis of diabetes, she has profound visual impairment despite correction for myopia, and has also developed marked autonomic neuropathy and diabetic nephropathy.

Adult↗
PubMed1983

Where did all the "No-Shows" go?

The pilot study examines the demographic profile, referral source, and presenting symptom of 40 families whose child was referred to and accepted for assessment by the Outpatient Psychiatry Department of the Hospital for Sick Children, but who ended up cancelling their initial assessment interview when an appointment time was set. These "No-Show" cases constitute a relatively small (13.6%) proportion of the total population accepted for assessment. the "No-Show" families did not differ markedly from the general intake population in terms of age, and presenting problem. However, girls, suburban residence and lower class background were more prevalent in the "No-Show" group. The length of time spent on the waiting list was given most frequently as the primary reason for cancelling the appointment.

Ambulatory Care↗
PubMed1979

Contingent negative variation and evoked potential amplitude as a function of inspired nitrous oxide concentration.

Nine subjects were given to breath 10%, 20%, 30% and 40% nitrous oxide in oxygen. The inhaled gas concentrations were monitored by a mass spectrograph. At each gas concentration the CNV was measured in a standard long S1-S2 CNV paradigm to a click and tone with a mandatory button press at S2. The results confirmed the previous observations of Lader and Morris (1974) that the cortical evoked potential decreases rapidly with increasing concentrations of nitrous oxide. The CNV, however, against prediction remains surprisingly well preserved up to the borders of unconsciousness. In this situation there is little correlation between CNV amplitude and attention, arousal or reaction time.

Adult↗
PubMed1977

Metabolic and EEG changes during transcendental meditation: an explanation.

Two experiments were conducted to measure the oxygen uptake (Experiment II) and the carbon dioxide production (Experiment I) during transcendental meditation. A control group of non-meditators and a few meditators listening to music was used for both experiments. In Experiment I, a controlled group of fasting meditators was also included. A drop in oxygen consumption and carbon dioxide production, found by previous authors during transcendental meditation, was confirmed. It was, however, possible to show that these drops were physiologically of small significance, and were of the magnitude to be expected from muscle relaxation. EEG recordings were taken during Experiment II in the meditating group. The EEG results showed transcendental meditation to be a method of holding the mediator's level of consciousness at stage 'onset' sleep. No evidence could be found to suggest that meditation produced a hypometabolic state beyond that produced by muscle relaxation and there was no evidence that the EEG changes were different from those observed in stage 'onset' sleep. No support was found for the idea that transcendental meditation is a fourth stage of consciousness.

Analysis of Variance↗