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Biomedical subjects

G A Harrison

Publications and source records attributed to G A Harrison.

At least 19 recordsLinked to original sources
PubMed1992

Some determinants of population variation in cortisol levels in a British urban community.

Urinary cortisol excretion rates were determined from three urine samples given over 2 days, a rest day and a working day, by 51 men and 50 women. Each subject also completed a questionnaire relating to life style factors and to perceived levels of stress, busyness and happiness on each day. In men, an association between raised cortisol and high levels of stress was found. In women, high levels of busyness were associated with low cortisol excretion rates. The subjective experiences measured accounted for around 10-20% of cortisol variation in this naturalistic setting.

Adult↗
PubMed1992

Inspiratory speech as a management option for spastic dysphonia. Case study.

A case study is reported of a subject who has used inspiratory speech (IS) for 6 years as a means of overcoming the communication problems of long-standing adductor spastic dysphonia (ASD). The subject was studied to confirm his use of IS, determine the mechanisms of its production, investigate its effects on ventilatory gas exchange, and confirm that it was perceptually preferable to ASD expiratory speech (ES). Results showed that the production and control of a high laryngeal resistance to airflow were necessary for usable IS. Voice quality was quantitatively and perceptually poor; however, the improved fluency and absence of phonatory spasm made IS the preferred speaking mode for both the listener and the speaker. Transcutaneous measurements of the partial pressures of oxygen and carbon dioxide in the subject's blood were made during extended speaking periods. These measurements indicated that ventilation was unchanged during IS, and that ventilation during ES was similar to the "hyperventilation" state of normal speakers. The reasons for the absence of phonatory spasm during IS are discussed, and the possibility of its use as a noninvasive management option for other ASD sufferers is addressed.

Airway Resistance↗
PubMed1992

Alveolar oxygenation and mouth-to-mask ventilation: effects of oxygen insufflation.

The effect on alveolar oxygen fraction (FAO2) of insufflating oxygen under a mask (or through an inflow nipple provided in the mask) during simulated mouth-to-mask ventilation was investigated using a lung model. A variety of commercially produced masks were evaluated. Two patterns of artificial ventilation were applied: 1. 500 ml tidal volume at 20 breaths per minute, and 2. 900 ml tidal volume at 12 breaths per minute. The ventilating gas mixture was oxygen 16% in nitrous oxide, and oxygen was insufflated at flow rates of 2, 4, 6, 8, 10, 12 or 14 litres per minute. The rate of rise of FAO2 and the equilibrium FAO2 attained were greatest at high oxygen inflow rates. The relationship between oxygen flow and FAO2 was not linear however, and an oxygen flow rate of 10 l/min was adequate to generate FAO2's around 50% with either ventilatory pattern. The equilibrium FAO2 achieved was greater with smaller tidal volumes and with larger mask deadspace. We also found that several breaths were required for equilibration of FAO2 during each trial, supporting recommendations that several breaths should be given on commencement of artificial ventilation during cardiopulmonary resuscitation.

Equipment Design↗
PubMed1992

A survey of Fellows of the Faculty of Anaesthetists of the Royal Australasian College of Surgeons endorsed in intensive care by examination in the first 10 years of final examinations in intensive care.

Fifty-nine of the 70 Fellows of the Faculty of Anaesthetists who had passed the Final Examination in Intensive Care including that of October 1989, responded to a questionnaire on the pattern of their intensive care and anaesthetic practice and their perception of the training and examination. Responses came predominantly from Fellows who had passed the examination more than two years previously. Forty-eight (81%) were practising intensive care at least 50% of the time and 51% had become Director or Deputy Director of an Intensive Care Unit. However, 51% maintained some anaesthetic practice. Although individuals had changed the intensive care/anaesthetic distribution of their practice, the group overall had not. With one exception all Fellows were practising in public hospitals but 26% in private hospitals also. Only eight had sought intensive care as their first vocational qualification. Training and examination were generally regarded favourably except for training in research methods and experience in internal medicine. The results suggest that the intensive care specialist is not likely to leave such practice in the long term, but there has been a reluctance to abandon altogether training and some subsequent practice in anaesthetics.

Anesthesia↗
PubMed1992

Effects of high iron and sulfate ion concentrations on dry matter digestion and volatile fatty acid production by ruminal microorganisms.

The inhibitory effects of iron- and sulfate-containing compounds on the in vitro digestion of a balanced forage diet by mixed populations of ruminal microorganisms were examined in batch cultures. Compounds containing ferrous and ferric cations consistently inhibited DM digestion by up to 36% when added Fe concentrations in cultures were between 100 and 1,000 mg/L. Increased sulfate concentrations of up to 200 mg/L or chloride concentrations of up to 635 mg/L were not associated with decreased DM digestion. Ammonium sulfate additions that provided 200 mg/L of added sulfur increased (P less than .05) digestibility by 10%. Sulfate-containing iron salts tended to be less inhibitory than chloride salts and were associated with increased gas production during digestion. Ferric chloride inhibited (P less than .05) microbial activities at lower concentrations than ferrous chloride. Data suggest that excessive iron supplementation or contamination of feeds with iron-containing pollutants may decrease microbial activities in the rumen.

Ammonium Sulfate↗
PubMed1992

Interrelations between growth, weaning and disease experience in Khartoum infants.

The monthly measurements of body weight and supine length from birth to 1 year of 203 infants in Khartoum were analysed to see whether growth characteristics affected the timing of weaning and the amount of illness experience. The study clearly shows that neonates who are long for their age tend to be weaned early, and this causes them to experience a greater average monthly 'illness experience' and slower subsequent growth. However, a multivariate analysis indicates that it is correlated environmental variables rather than length growth itself which primarily determines weaning age. Weight growth does not show these relationships but there is strong evidence that late weaning, independently of disease experience, promotes post-natal weight growth.

Body Height↗
PubMed1991

Urinary catecholamines, plasma insulin and environmental factors in relation to body fat distribution.

The relationship of body fat distribution to insulin and the catecholamines, hormones that affect lipolysis differentially by fat site, was examined within an environmental context, including factors of medication use, physical activity, dietary intake, educational attainment, and age. Four cross-sectional body fat areas (cm2) were determined by three computed tomography (CT) scans (subcutaneous chest fat at the level of the nipples, subcutaneous and intra-abdominal fat at the level of the umbilicus, and subcutaneous left mid-thigh fat) in 191 second-generation Japanese-American men aged 45-74 years. The site-specific fat measurements were first examined in relation to use of beta-adrenergic antagonists, then to fasting plasma insulin and C-peptide levels and to urinary epinephrine and norepinephrine levels from a 24-h urine collection made during usual daily activities. Greater fat stores in the intra-abdominal area, even after adjustment for body mass index (BMI, weight/height2) and presence of coronary heart disease, were found to be related to use of beta-adrenergic antagonists. In men taking no adrenergic antagonists (n = 157), after adjustment for BMI, truncal fat measurements of the chest (partial r = -0.16, P less than 0.05) and intra-abdominal area (partial r = -0.21, P less than 0.05) were found to be inversely related to epinephrine, and intra-abdominal fat (partial r = 0.25, P less than 0.01) alone was directly related to fasting plasma insulin. With respect to other environmental variables, the significant inverse relationship of intra-abdominal fat (adjusted for BMI) with physical activity (partial r = -0.17, P less than 0.05) and the significant difference in intra-abdominal fat by educational attainment (college 102.3 +/- 5.7 vs no college 115.7 +/- 6.1 cm2, P = 0.03) became non-significant with adjustment, using multiple regression analysis, for insulin in the case of physical activity and epinephrine in the case of educational attainment. Thus, intra-abdominal fat showed a unique set of relationships to metabolic parameters which could be further related to certain environmental variables.

Adipose Tissue↗
PubMed1991

Geographic distributions of within-population variability in blood pressure.

Data on mean blood pressure with standard deviation were extracted from the medical and anthropologic literature for as many populations as possible. The populations were classified as traditional, transitional, or modern. Both mean and within-population variability were found to be higher in more modern populations, confirming the prediction that variability of a character of low heritability is higher in an adverse environment, where it is more difficult to maintain homeostasis. In addition, variability increases with age, indicating a breakdown in homeostasis with aging. On average, males had higher diastolic blood pressure than females, and on average, females had greater variability in systolic blood pressure than males. There was a highly significant negative relationship between latitude and within-population variability in blood pressure.

Adult↗
PubMed1990

Pseudomonas aeruginosa orbital cellulitis in four neutropenic patients.

Four neutropenic patients on a haematology ward developed orbital cellulitis due to different strains of Pseudomonas aeruginosa over a 7-month period. Investigation of patients and the ward environment revealed two P. aeruginosa isolates indistinguishable from the infecting strains in a plastic washing bowl and a sink in a single cubicle respectively. These items were unlikely to have been the sources of the infecting strains but were a potential cross infection hazard. Treatment of orbital cellulitis is discussed briefly.

Adolescent↗
PubMed1990

Components of growth variation in human stature.

Traditional methods of estimating the heritability of a trait such as height utilize a single observation of the variance. This, however, provides little insight into the way in which the variance is generated. In this paper, we propose that repeat measurements of height over a period of childhood growth can be used to estimate different components of the variation in height increment. By height increment we mean the successively longer increments computed relative to a common initial height. Models are developed which indicate that the genetic component of the variance accumulates as a quadratic function of the mean, while the environmental component accumulates until it reaches a constant. This 'homeostatic constant' represents an equilibrium between the input of environmentally induced variation and its removal through homeostasis. Large constants are indicative of poor environments and poor homeostatic responses. The constant therefore provides a measure of the adaptive status of the children at the level of the population. The models are here applied to growth data collected on Hong Kong infants. The resulting estimate of the genetic component of the variance is 0.0044 cm2 per cm2 of mean height increment. This is somewhat higher than expectation but easily accounted for through the effects of environmental stratification on the variance. The homeostatic constant is estimated to be approximately 1.2 cm2. This is the first such estimate of its kind.

Analysis of Variance↗
PubMed1990

Baseline activated coagulation time should be measured after surgical incision.

The activated coagulation time (ACT) is widely used to guide heparin and protamine dosing during cardiac surgery. A common protocol involves establishing a baseline ACT before administering heparin, then using this ACT as a target value for assessing the adequacy of heparin neutralization after cardiopulmonary bypass. Results vary in previous comparisons of baseline ACT to postprotamine ACT, with some showing postprotamine ACT significantly below baseline values. The present study examined ACTs at three possible baseline intervals in 68 patients at two institutions: (a) before anesthetic induction; (b) after anesthetic induction; and (c) after sternotomy. Baseline ACT decreased significantly with anesthesia and surgery. The poststernotomy baseline ACT best matched the postprotamine ACT. It appears likely that surgery induces a thromboplastic response that decreases ACT. Establishing baseline ACT before anesthetic induction would predispose to false diagnoses of adequate protamine neutralization after cardiopulmonary bypass, because ACT is relatively insensitive to low concentrations of unneutralized heparin. Baseline ACTs should therefore be measured after surgical incision.

Aged↗
PubMed1990

Cross-infection and diversity of Candida albicans strain carriage in patients and nursing staff on an intensive care unit.

Colonization of patients and nursing staff on an intensive care unit by Candida albicans was studied over a 4-month period. Multiple swabs and samples were taken from patients and their nurses on 12 occasions during the study period. During this study there were no obvious clinically relevant candidal infections. Patients yielded C. albicans from at least one body site on 68%, and nurses on 57% of occasions. All isolates of C. albicans were further characterized by both morphotyping and resistotyping. All patients but one were colonized by a single strain throughout their stay on the unit, whereas nurses were often colonized by more than one strain type. Strains isolated from nurses' hands were all indistinguishable from strains colonizing the patient under their care, whilst strains isolated from nurses' mouths were usually distinct from their patients'. The probability that a C. albicans culture positive nurse carried an indistinguishable strain from that of her positive patient was p = 0.632, compared with p = 0.325 that a randomly chosen positive nurse would carry a strain indistinguishable from that of a randomly chosen positive patient. Diversity in patients' strains was low (D = 0.667) compared with nurses' strains (D = 0.778). These results suggest that cross-infection by C. albicans is a common occurrence on intensive care units. The reason outbreaks of candidal disease are not more common may be related to differences in virulence of the strains.

Candida albicans↗
PubMed1989

Open cardiac compression in the postoperative cardiac intensive care unit.

Thirty-nine patients required heroic resuscitative measures for sudden hypotension and cardiac arrest in the first 72 hours following cardiac surgery between January 1, 1984 and May 31, 1988. Emergency sternotomy with open cardiac compression was performed in twenty-four of these patients when external cardiac compression failed. These were categorised as Group A. Group B comprised the fifteen patients in whom resuscitation was entirely by means of external compression and adjuvant measures. Survival with NYHA Functional Class I and II status was noted in 75% of patients in Group A, compared with 20% in Group B (P less than 0.002). Emergency sternotomy with open cardiac compression is an effective way of resuscitating patients in the intensive care unit in the first few days following open heart surgery.

Cardiac Surgical Procedures↗