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Biomedical subjects

M Elia

Publications and source records attributed to M Elia.

At least 19 recordsLinked to original sources
PubMed1997

A new family with periventricular nodular heterotopia and peculiar dysmorphic features. A probable X-linked dominant trait.

OBJECTIVE: To describe 3 sisters with brain periventricular heterotopia and peculiar dysmorphic features as a probable X-linked dominant trait. DESIGN: Clinical, laboratory, neurophysiological, and brain imaging data were studied. SETTING: Research institute for mental retardation. PATIENTS: The 3 sisters had mental retardation, drug-resistant epilepsy, gray matter heterotopia, and peculiar malformations (low nasal bridge, upslanting palpebral fissures, palpebral edema, attached hypoplastic earlobes, thickened calvaria, rectal fibrovascular polyps, urinary tract anomalies, and increased foot length). The patients were 35, 30, and 25 years old and belonged to a sibship of 6, born of nonconsanguineous healthy parents. CONCLUSION: The 3 patients constitute a well-defined clinical entity not previously described of a probable X-linked dominant nature.

Adult↗
PubMed1996

International Federation of Clinical Chemistry. Laboratory assessment of protein-energy status.

Laboratory and non-laboratory methods for assessing protein-energy nutritional status are reviewed. These are classified into methods for assessing adequacy of recent nutritional intake, methods for assessing whole body status, and tests which assist in the interpretation of these assessments. Each measurement is critically discussed in terms of the rationale for its use, the method of analysis, reference values, technical interference and limitations of methods, the effects of nutritional status and of other factors on the results, its overall usefulness in nutritional assessment, and its value relative to other methods. Non-laboratory tests such as dietary assessment, indirect calorimetry, functional tests and the many methods available for assessment of body composition, including anthropometry, bioelectrical impedance and isotope and imaging techniques, are compared with the clinical chemistry tests in common use, such as nitrogen balance, plasma protein measurements and urinary markers of muscle metabolism. This review provides comprehensive and practical advice on the use and limitations of these tests in the assessment of protein-energy nutritional status of a group, or of an individual patient.

Calorimetry↗
PubMed1996

Relationship between anthropometric indices of body fat distribution and basal energy metabolism in healthy Maltese women.

A sample taken from a population (Maltese) with a high incidence of the metabolic complications of central obesity was studied to determine: (1) whether the standard Schofield equations adequately predict the basal metabolic rate (BMR) in this population; (2) whether the Maltese have a greater tendency for central obesity compared with other populations; (3) whether the distribution of body fat influences energy expenditure and fuel selection. Healthy women responding to a public advertisement were sampled randomly from the Maltese population. Correlation analysis and analysis of variance were used to study relationships between BMR and body composition. Anthropometric parameters (including body fat distribution indices, bioimpedance) and BMR were measured after an overnight fast. Six percent of the respondent were excluded because of recent illness, instability of diet or of body weight. Fifty subjects attended a clinic at the Medical School. The distribution of excess fat between central and peripheral areas in the Maltese population was similar to that reported for the British population. The Waist-hip ratio (WHR) reflected neither basal heat production (BMR) nor the contribution of fat oxidation to BMR. The Schofield equations systematically underestimated BMR by 5.4% +/- 0.86% (P < 0.05). The study suggests a limitation in using the Schofield equations for predicting BMR in the female Maltese population studied. It also suggests that the fat distribution between central and peripheral areas in this population has no effect on BMR.

Adipose Tissue↗
PubMed1996

Chaotic behavior of EEG slow-wave activity during sleep.

The study of the dynamics of non-linear systems allows the evaluation of the correlation dimension which, in turn, provides an estimate of the number of variables needed to model the process. In such a view, the correlation dimension was calculated for the profiles of the EEG slow-wave activity during sleep obtained from 7 young normal controls and in their corresponding artificial stochastic signals. It was possible to evaluate the complexity of all the real profiles which exhibited an average dimension of 3.76 (SD 0.331), but not that of the artificial control ones. This allows us to conclude that sleep regulation might be considered as a deterministic non-linear process and that the already proposed two-process model of sleep regulation needs to include additional variables with non-linear interactions.

Adolescent↗
PubMed1996

Scalp topographic mapping of middle-latency somatosensory evoked potentials in normal aging and dementia.

Middle-latency somatosensory evoked potentials (MLSEPs) were recorded in four groups of subjects: 13 normal young controls (mean age, 17.9 years). 11 normal elderly (mean age, 66.9 years), 11 patients with dementia of Alzheimer's type (DAT: mean age, 70.5), and four with vascular dementia (mean age, 79.3). MLSEPs in normal elderly showed an increase in the latency of P22, N30, P45, N60, and P100, and in the amplitude of N60. DAT patients also presented such changes; however, the increase in the amplitude of N60 was much more evident than that found in normal aging and was accompanied by a significant increase in amplitude of P45. Patients with vascular dementia tended to show longer latencies and larger amplitudes than the other groups. The increase in amplitude of P45 and N60 in MLSEPs seems to be characteristically associated with normal aging and the development of dementia. It is suggested that the mechanism of such functional changes might be correlated with the structural and neurochemical changes accompanying neuronal loss in these conditions.

Adolescent↗
PubMed1996

Age-and height-dependent changes of amplitude and latency of somatosensory evoked potentials in children and young adults with Down's syndrome.

Middle-latency somatosensory evoked potentials (MLSEPs) were recorded from 19 scalp electrodes in 34 patients with Down's syndrome (DS) aged 7.4 to 35.7 years and in 16 normal control subjects aged 6.4 to 34.4 years. DS patients showed an increase in amplitude of P22, P45, and N60. P100 latency was significantly shortened. After normalization for height of subjects, N20 and N60 latencies were significantly longer in the patient group than in control subjects. On the other hand, it was possible to observe in both groups a significant trend for MLSEP amplitudes to decrease with age during the age period considered in this work. This study further confirms that the pattern of increase in amplitude of MLSEP components observed in DS is a finding peculiar of this syndrome and is not correlated with early aging processes.

Adolescent↗
PubMed1996

Total energy expenditure and physical activity measured with the bicarbonate-urea method in patients with human immunodeficiency virus infection.

1. Our objectives were to measure total energy expenditure, the daily variation in total energy expenditure and the physical activity level in a group of HIV-positive subjects using the bicarbonate-urea method. The study also aimed to asses the practicalities of using the bicarbonate-urea technique in free-living conditions. 2. Total energy expenditure was measured with the bicarbonate-urea method over 2 consecutive days (1 day in one subject) in 10 male patients with HIV infection (median CD4 count = 30). Resting energy expenditure was measured by indirect calorimetry. Physical activity level (total energy expenditure/resting energy expenditure) was calculated from these measurements and from activity diaries. 3. Resting energy expenditure was found to be 7.46 +/- 0.87 MJ/day, 5% higher than predicted values. Total energy expenditure was 10.69 +/- 1.95 MJ/day with an intra-individual day-to-day variation of 6 +/- 6%. The measured physical activity level was 1.42 +/- 0.14, higher than the diary estimate of 1.34 +/- 0.16 (P = 0.029), and there were large intermethod differences in individual values. The subcutaneous infusion of bicarbonate was well tolerated and did not seem to restrict normal activities. 4. Total energy expenditure was not elevated in the group of HIV-positive subjects when compared with reference values for normal subjects. The physical activity level of the patients in this study was lower than that measured using other techniques in healthy young men, but was compatible with that expected for people leading a sedentary lifestyle. Reductions in physical activity in patients with HIV are likely to contribute to the wasting process and physical activity level may thus be a clinically useful measure. This study has also provided the first tracer estimate of the day-to-day variation in total energy expenditure. The bicarbonate-urea method represents an important new investigative tool for measuring total energy expenditure which has previously only been possible within the confines of a whole-body calorimeter or using the expensive doubly labelled water method.

Adult↗
PubMed1996

Recovery of 13CO2 and 14CO2 in human bicarbonate studies: a critical review with original data.

1. In order to establish biological and/or methodological explanations for the wide variability in recovery (50-100%) of labelled CO2 after administration of [13C]bicarbonate or [14C]bicarbonate, 34 human bicarbonate studies involving 480 subjects were analysed, and potential methodological issues were investigated in the laboratory. 2. Overall, continuous infusion studies reported a higher recovery than bolus studies (84 +/- 11% versus 69 +/- 12%; P < 0.001). No significant differences in recovery were found between 14C and 13C studies, children and adults, obese and lean subjects, or rest and exercise (steady state). Higher recoveries were found during feeding than during fasting (84 +/- 8% versus 74 +/- 7%; P < 0.001). Different methods used to analyse the results (0-10%) and different study protocols, which include differences in the duration of infusions and background drift in 13C enrichment (0-10%), contribute to the variability. 3. The laboratory studies suggest multiple sources of potential error, including loss of CO2 from the scintillation fluid (up to > 30%, but only in 14C studies in which the scintillation fluid is not alkalized), diffusion of CO2 through syringes and tubing (0 to > 10%), non-linearity of CO2 analysers (up to 8%), inaccuracies in the measurement of bicarbonate concentrations (13C studies) or the strength of CO2-trapping agents (14C studies; 0-8%). 4. It is concluded that much of the variability in the recovery of labelled bicarbonate is likely to be attributable to methodological differences, and that attention to these will ensure better interpretation of metabolic studies that involve oxidation of carbon-labelled substrates.

Adult↗
PubMed1996

Changes in protein distribution in normal and protein-deficient rats during an acute-phase 'injury' response.

The present study investigated the effect of the acute-phase 'injury' response, induced by subcutaneous injection of turpentine, on the hydration and protein content of organs and tissues of normally nourished rats receiving a diet containing 200 g protein/kg, and of protein-malnourished rats receiving a diet containing 30 g protein/kg. The measurements were carried out 48 h after turpentine injection, and were compared with both saline-injected animals, and pair-fed control animals. Circulating alpha 2-macroglobulin was also measured as an index of the acute-phase-protein response. In normally nourished rats turpentine injection caused a significant increase in the mean masses of the liver, kidney and lung (7-35% compared with saline-injected animals, and 20-44% compared with pair-fed controls), and a small reduction in the mass of extra-abdominal and extrathoracic tissues ('carcass'). In general the protein content of tissues changed in a similar way (for liver, kidney and lung a 16-33% increase compared with saline-injected animals, and 32-49% compared with pair-fed controls). Protein deficiency produced a significant attenuation in the response to turpentine. The change in the mass and protein content of several tissues was reduced (for lung, liver and kidney, the increase in protein content was only 5-15%), and the effects on anorexia (1 v. 41% reduction in food intake) and the alpha 2-macroglobulin response (1.28 v. 4.28 g/l; P < 0.001) were also reduced. It is concluded that the injury response spares most central thoracic and abdominal organs, but this effect as well as the anorexia and acute-phase-protein response to injury are attenuated by protein deficiency.

Acute-Phase Reaction↗
PubMed1996

Components of total energy expenditure in free-living elderly men (over 75 years of age): measurement, predictability and relationship to quality-of-life indices.

Current recommendations for energy requirements in the elderly are based on assumed levels of physical activity relative to BMR (1.5 x BMR). The main aim of the present study was to establish whether these recommendations might be applicable to a randomly-selected group of free-living elderly men (all over 75 years of age). BMR was measured by indirect calorimetry and total energy expenditure (TEE) by the doubly-labelled-water technique. Further aims included evaluating the applicability of a variety of BMR prediction equations and whether assessed quality of life reflected any measured indices of energy expenditure. The mean value for daily energy requirement was found to be 1.5 x BMR (89 J/kg per min) but with substantial inter-individual variation (sd 0.2 x BMR; 14 J/kg per min). The bias between measured TEE and TEE estimated (1.5 x BMR) from the various BMR predictions varied according to which equation was used (-10- + 8% of the mean) with substantial 95% limits of agreement (28-30% of the mean). TEE and physical activity plus thermogenesis (TEE-BMR) were positively related to activities of daily living, but no relationships were apparent between these and perceived quality of life. It is concluded that, despite considerable inter-individual variability, national recommendations for energy requirements of elderly people are applicable to this randomly-selected group of free-living men over 75 years of age but that substantial variation exists when attempts are made to estimate TEE from measurements or predictions of BMR.

Activities of Daily Living↗
PubMed1996

Dual-energy X-ray absorptiometry for the measurement of gross body composition in rats.

Dual-energy X-ray absorptiometry (DXA) is a novel, non-invasive technique for the measurement of gross body composition in small animals. In the present study the absolute accuracy of the Hologic QDR-1000W scanner was assessed by comparison with direct analysis in twelve rats with a range of body fat and bone mineral content (BMC) values. Fat masses measured by DXA and petroleum-ether extraction were significantly different (P < 0.0023). The DXA technique consistently overestimated fat mass by approximately one third of the measured fat content. BMC derived from the measurement of Ca in ash gave a mean of 8.26 (range 1.57-15.71)g. BMC measured by DXA was not significantly different for the group as a whole. However, there was a trend for DXA to overestimate BMC in animals with low BMC and underestimate in those with higher BMC, compared with direct analysis, such that the 95% limits of agreement for the two techniques were +2.73 to -2.58 g. These results suggest that the present small-animal software developed for use with currently available Hologic machines does not give an accurate measure of gross body composition compared with the results from classical direct analysis.

Absorptiometry, Photon↗
PubMed1996

Home enteral tube feeding in East Anglia.

OBJECTIVE: To establish the profile of patients receiving home enteral tube feeding (HETF) in East Anglia, to assess the adequacy of care, and to consider the causes and implications of differences in the geographic prevalence of HETF. DESIGN: A 1-year prospective study. SETTING: Eight independently funded districts within East Anglia. SUBJECTS: Basic clinical data were available from 234 patients, 191 of which were tube-fed in the same district as that which initiated treatment, with detailed data obtained from 126. OUTCOME MEASURES: Prevalence, complications in relation to the dietetic support available, and standards of care in relation to those set in the reports of the King's Fund and the British Association of Parenteral and Enteral Nutrition. RESULTS: The patients, who were usually elderly subjects or children, had severe disabilities: 40% were unable to walk: 39% were unable to speak; and 20% were housebound. In all cases enteral tube feeding had been initiated in hospital but in this survey we found inadequate training for home care in 23%, inadequate support and follow-up in 20%, inadequate equipment in 41%, uncertainties regarding organisation, and various clinical problems such as feed regurgitation, in 22%, aspiration pneumonia in 13% , which occasionally led to hospitalization (4%), and frequent but usually minor peristomal problems in patients with gastrostomies. There was a direct correlation between the prevalence of HETF (which varied fourfold between districts) and the number of NHS dieticians per head of population; and in inverse correlation with respect to requests by patients for more support (r = 0.97), complaints of blocked tubes (r = 0.82) and the need for hospital help. CONCLUSION: HETF provides an important form of support to a small group of severely disabled patients. There are important differences between districts in the prevalence of HETF which may be related to variation in local expertise and available support staff. The standards of care did not always conform to those set in the King's Fund report and BAPEN report on Enteral and Parenteral Nutrition in the community.

Adolescent↗
PubMed1996

Evaluation of multiple frequency bioelectrical impedance and Cole-Cole analysis for the assessment of body water volumes in healthy humans.

OBJECTIVE: To assess the application of a Cole-Cole analysis of multiple frequency bioelectrical impedance analysis (MFBIA) measurements to predict total body water (TBW) and extracellular water (ECW) in humans. This technique has previously been shown to produce accurate and reliable estimates in both normal and abnormal animals. DESIGN: The whole body impedance of 60 healthy humans was measured at 496 frequencies (ranging from 4 kHz to 1 MHz) and the impedance at zero frequency, Ro, and at the characteristic frequency, Zc, were determined from the impedance spectrum, (Cole-Cole plot). TBW and ECW were independently determined using deuterium and bromide tracer dilution techniques. SETTING: At the Dunn Clinical Nutrition Centre and The Department of Biochemistry, University of Queensland. SUBJECTS: 60 healthy adult volunteers (27 men and 33 women, aged 18-45 years). RESULTS: The results presented suggest that the swept frequency bioimpedance technique estimates total body water, (SEE = 5.2%), and extracellular water, (SEE = 10%), only slightly better in normal, healthy subjects than a method based on single frequency bioimpedance or anthropometric estimates based on weight, height and gender. CONCLUSIONS: This study has undertaken the most extensive analysis to date of relationships between TBW (and ECW) and individual impedances obtained at different frequencies ( > 400 frequencies), and has shown marginal advantages of using one frequency over another, even if values predicted from theoretical bioimpedance models are used in the estimations. However in situations where there are disturbances of fluid distribution, values predicted from the Cole-Cole analysis of swept frequency bioimpedance measurements could prove to be more useful.

Adolescent↗
PubMed1996

Automated assay of plasma bromide after a single deproteinization step.

This study aimed to simplify the spectrophotometric fluorescein method for measuring plasma bromide, improve its reproducibility, and automate it. After major modifications of the method, we obtained an essentially linear calibration curve for plasma concentrations of bromide between 0 and 5.0 mmol/L. The intraassay CV for measuring bromide in the supernatants of deproteinized plasma samples (initial plasma concentrations 2.5-5.0 mmol/L) was as low as 0.5-1.0% (n = 9). When all the procedures were incorporated, including deproteinization and dilution of plasma, the intraassay CV was 2% at 2.5 mmol/L (n = 5) and 1% at 5.0 mmol/L (n = 5). The interassay CV for measuring bromide in plasma supernatants (initial plasma bromide concentration > 2.5 mmol/L) was 1%. Analytical recovery of bromide added to plasma was 99.1% +/- 2.5%. The new method is simpler and more reproducible than other spectrophotometric methods. Conditions for its automation are described.

Autoanalysis↗
PubMed1996

Circadian patterns of total 24-h hydrogen and methane excretion in humans ingesting nonstarch polysaccharide (NSP) diets and the implications for indirect calorimetric and D2 18O methodologies.

OBJECTIVES: To quantify the relationship between substrate fermentation and total 24-h H2 and CH4 excretion on mixed diets and to assess errors incurred in the calculation of energy expenditure and fuel selection by the exclusion of these gases from standard calculations. DESIGN AND SUBJECTS: Twelve healthy, lean men were studied over two consecutive dietary periods of 3 weeks. Measurements of total H2 and CH4 excretion were made during 24h within a whole body calorimeter. Subjects were fed a diet containing 16 g or 38 g of nonstarch polysaccharide (NSP) and 16 g or 19 g resistant starch (RS). Colonic fermentation was measured by balance techniques during the two dietary treatments. RESULTS: There was an inverse non-linear relationship between H2 and CH4 excretion on both diets (r2 = 0.53; P < 0.001), but absolute excretion did not increase significantly as the intake of NSP and RS (from 28 +/- 3 and 48 +/- 4 g/day) increased. No relationship was found between daytime and 24-h measurements of H2 and CH4. H2 and CH4 excretion introduces an error of less than 0.2% and 1% in calculations of energy expenditure and CO2 production from the standard human equations used in indirect calorimetric (IC) and doubly labelled water (DLW) methodologies respectively, and less than 2% in fuel utilisation calculated as % non-protein energy expenditure from IC. CONCLUSIONS: This study provides evidence that neither daytime nor total 24-h rates of H2 or CH4 excretion accurately predict degree of fermentation of NSP+RS in either individual subjects or groups of subjects, probably because of changes in the stochiometry of the fermentation process.

Adult↗
PubMed1995

Haemodynamic responses in muscle and adipose tissue and whole body metabolic responses during norepinephrine infusions in man.

Circulatory metabolic and cardiovascular responses to 1-h-long infusions of norepinephrine (NE) (approx. 0.2 and 0.4 nmol/kg body weight per min) were measured on two separate occasions in six subjects. The infusions increased circulating NE concentrations 6- and 13-fold, respectively. Blood flow to adipose tissue, measured with the 133Xe clearance technique, increased from a basal value of about 3 ml/100 g per min, to about twice this value at 60 min with both doses of NE. In contrast muscle blood flow was unaffected. The higher dose of NE produced significant increments at 60 min in whole body oxygen consumption (approx. 9%), and circulating concentrations of glucose (approx. 18%), non-esterified fatty acids (approx. 200%) and glycerol (approx. 32%) which were greater than those observed with the low-dose infusion. Changes in blood pressure, pulse and CO2 exchange were observed within 5-10 min after the start of the infusion, whilst changes in adipose tissue blood flow were observed after 15-30 min. It is concluded that in humans (i) a dose of NE as low as 0.2 nmol/kg per min is sufficient to evoke both circulatory and metabolic responses; (ii) the pattern in the adipose tissue blood flow response to NE may help explain some of the conflicting reports about the haemodynamic effects of this hormone in adipose tissue; and (iii) blood flow and vascular resistance in different tissues may be affected in different ways by norepinephrine.

Adipose Tissue↗