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E Milne

Publications and source records attributed to E Milne.

At least 55 records · Page 3Linked to original sources
PubMed1997

Maternal cannabis use and birth weight: a meta-analysis.

AIMS: To estimate the effect of maternal cannabis use on birth weight. DESIGN: Meta-analysis of published observational studies adjusted for cigarette smoking. Separate analyses were performed for studies of low birth weight and mean birth weight. We used fixed and random effects models, but in all cases the results were identical. SETTING: From the Medline database, we identified 10 studies in which the results were adjusted for cigarette smoking. In seven studies, information on cannabis use was collected prenatally. Five studies reported results for differences in mean birth weight associated with maternal cannabis use. PARTICIPANTS: 32,483 women giving birth to live-born infants. MEASUREMENTS: Mean birth weight and odds ratio for low birth weight. FINDINGS: Three analyses of the studies on mean birth weight were conducted to avoid double-counting women from one study. The largest reduction in mean birth weight for any cannabis use during pregnancy was 48 g (95% confidence interval (CI) 83-14 g), with considerable heterogeneity among the five studies. Mean birth weight was increased by 62 g (95% CI 8 g reduction-132 g increase; p heterogeneity 0.59) among infrequent users (< or = weekly) whereas cannabis use at least four times per week had a 131 g reduction in mean birth weight (95% CI 52-209 g reduction; p heterogeneity 0.25). From the five studies of low birth weight, the pooled odds ratio for any use was 1.09 (95% CI 0.94-1.27, p heterogeneity 0.19). CONCLUSIONS: There is inadequate evidence that cannabis, at the amount typically consumed by pregnant women, causes low birth weight.

Birth Weight↗
PubMed1997

Maternal cocaine use and low birth weight newborns: a meta-analysis.

AIM/DESIGN: Many epidemiological studies published on the association between maternal cocaine/crack use and birth weight have either lacked precision or failed to control for major confounding, predominantly by tobacco smoking. Meta-analysis enables a single summary measure of effect to be calculated by combining data from any number of individual studies, thus enhancing statistical power. We undertook a number of meta-analyses using only studies that had adjusted for tobacco smoking to estimate more precisely the effect of maternal cocaine use on birth weight. FINDINGS: A meta-analysis of five studies presenting data for 'any' prenatal cocaine exposure, adjusted for tobacco smoking but unadjusted for gestational age, produced a pooled relative risk estimate from a fixed effects analysis of 2.15 (95% CI 1.75-2.64). However, there was substantial heterogeneity among studies (p < 0.001), and the relative risk from a random effects analysis was smaller (1.65) with a confidence interval that included unity (95% CI 0.94-2.83). Addition of a further study adjusted for gestational age had minimal effect on the pooled estimate: the fixed effects relative risk was 2.14 (1.77-2.60) and the random effects estimate 1.77 (1.15-2.71). When data on more intense prenatal exposure were analysed, the fixed and random effects analysis produced the same pooled estimate of the relative risk of 4.42 (2.24-8.71), suggesting that more frequent cocaine exposure was associated with a higher relative risk for low birth weight. Data from studies on mean reduction in birth weight produced a pooled estimate of 112 g (95% CI 62-161 g). CONCLUSIONS: The current study suggests that maternal cocaine use causes low birth weight, and that the effect is greater with heavier use. However, despite the adjustment for tobacco and the adjustment by some studies for other confounders such as race, maternal age, gravidity and socio-economic status, it could be argued that other life-style factors not controlled for may account for the observed effects. While this argument is not supported by some other types of study, the issue of residual confounding can only be finally addressed by analytical studies which adequately control for important variables.

Cocaine↗
PubMed1997

The relationship between maternal use of heroin and methadone and infant birth weight.

UNLABELLED: AIMS/DESIGN: Reduction in mean birth weight and increased incidence of low birth weight are both associated with exposure to illicit heroin in pregnancy. Many studies examining neonatal outcomes in pregnant heroin users treated with methadone report improvements in birth weight. As a consequence, methadone treatment has become the 'gold standard' for the management of the pregnant heroin user. However, not all studies report significant birth weight increases associated with methadone. We undertook a number of meta-analyses on reduction in mean birth weight and incidence of low birth weight to estimate more precisely the effect of illicit heroin and methadone. FINDINGS: Results showed mean reduction in birth weight associated with heroin use: 489 g (95% CI 284-693 g), compared with methadone: 279 g (229-328 g). Similarly, the pooled relative risk estimate for low birth weight for maternal heroin use was 4.61 (95% CI 2.78-7.65), compared with 1.36 (0.83-2.22) for methadone. Analysis of data on combined heroin and methadone use produced a pooled mean reduction in birth weight of 557 g (403-710 g), with a pooled relative risk estimate for low birth weight of 3.28 (2.47-4.39). Pooling 'any' methadone data, regardless of heroin use, produced an estimated reduction in birth weight of 395 g (311-478 g) and a relative risk estimate for low birth weight of 1.90 (1.29-2.81). Combining all data in an 'any' opiate use analysis also produced a mean reduction in birth weight of 483 g (386-583 g) and a relative risk estimate for low birth weight of 3.81 (2.57-5.65). CONCLUSIONS: The current findings suggest that heroin use while receiving methadone may counteract the birth weight advantage gained from methadone alone. Whether this is due to fetal exposure to heroin plus methadone, to reduced antenatal care, other behavioural and environmental factors associated with concurrent use of heroin and methadone or a combination of these is unclear. Nevertheless, these results challenge the current belief that the pregnant user is always better off receiving methadone than not, and suggests that methadone may not be the appropriate treatment for the pregnant women who continue to use illicit heroin.

Birth Weight↗
PubMed1996

Meta-analysis of alcohol and all-cause mortality: a validation of NHMRC recommendations.

OBJECTIVE: To compare the National Health and Medical Research Council (NHMRC) recommendations on responsible, hazardous and harmful alcohol intake with their effects on all-cause mortality in men and women and on the occurrence of 10 specific neoplastic, cardiovascular and alimentary diseases. DESIGN: Meta-analyses of relative risks of mortality in relation to usual level of alcohol intake pooled from 16 cohort studies (mostly of adults over 35 years), and alcohol and selected conditions from a further 132 epidemiological studies. Results reported by authors were assigned to sex-specific exposure categories defined by the NHMRC based on median alcohol intakes. Pooled estimates of relative risk were calculated using precision-based weighting. SETTING: The assessment was part of comprehensive meta-analysis of epidemiological research undertaken for the National Drug Strategy. RESULTS: Relative risk of all-cause mortality in male drinkers compared with abstainers fell to 0.84 at 1.0-1.9 standard drinks per day, returned to 1.01 by 3.0-3.9 drinks, and increased to 1.37 at six or more drinks. In female drinkers the lowest relative risk (of 0.88) was at 0-0.9 drinks per day, and by 2.0-2.9 drinks the risk exceeded that in abstainers by 1.13; at six drinks the relative risk was 1.58. Based on NHMRC categories, the relative risks of mortality were 0.93 (0.93-0.94) in responsible drinkers, 1.24 (1.22-1.27) in hazardous drinkers and 1.37 (1.35-1.49) in harmful drinkers. Risk of cancers of the oropharynx, oesophagus, liver, larynx and female breast and of cirrhosis of the liver increased with increasing alcohol intake level. CONCLUSIONS: A pattern of usual alcohol intake consistent with the NHMRC recommendations will confer a mortality risk similar to or less than that observed in abstainers. The biologically effective dose of alcohol on mortality in women is approximately two standard drinks per day less than in men. Our validation is most reliable for drinkers aged 35 years or older.

Adult↗
PubMed1996

The fate of absorbed and exogenous ammonia as influenced by forage or forage-concentrate diets in growing sheep.

Changes in splanchnic energy and N metabolism were studied in sheep, prepared with vascular catheters across the portal-drained viscera (PDV) and the liver, and maintained on supramaintenance intakes of either gross or grass + barley pellets. The animals were challenged, on both diets, with 4 d intramesenteric vein infusions of NH4Cl (25 mumol/min) plus NH4HCO3 (at either 0 or 125 mumol/min). On the final day of each treatment the natural abundance NH4Cl was replaced with 15NH4Cl over a 10 h infusion while over the same period [1-13C]leucine was infused via a jugular vein. Measurements were made of blood flow plus mass transfers of NH3, urea, free amino acids and O2 across the PDV and liver. Enrichments of [14N15N]urea and [15N15N]urea plus [15N]glutamine, aspartate and glutamate were also monitored. Whole-body urea flux was determined by infusion of [14C]urea. At the end of the study the animals were infused for 3 h with 15nH4Cl, killed and liver samples assayed for intracellular free amino acid enrichments and concentrations. Blood flows across the splanchnic region were unaffected by either diet or level of ammonium salt infusion. At the lower ammonium salt infusion there was a trend for greater absorption of NH3 across the PDV (P < 0.10) with grass + barley than with the grass diet, while removal of urea was unaltered. At the higher ammonium salt infusions there was a significantly greater appearance of NH3 across the PDV and this exceeded the extra infused. Urea-N removal, however, was also elevated and by more than that required to account for the additional NH3. The PDV contributed 19-28% to whole-body O2 consumption and the liver 23-32%. Hepatic extraction of absorbed NH3 was complete on all treatments and systemic pH remained constant. The fractions of urea-N apparently derived from NH3 were similar on the grass (0.50-0.64) and grass + barley (0.64-0.67) diets. Hepatic production of urea agreed well with urea flux measurements. Between the two levels of ammonium salt infusion and within diets the additional NH3 removed across the PDV was accounted for by the increased urea-N production. The [14N15N]:[15N15N] ratio of the urea produced was 97:3, while the enrichment of hepatic intracellular free aspartate was lower than that of [14N15N]urea. Glutamine enrichments were 0.23-0.37 those of [14N15N]urea, indicating a minor role for those hepatocytes (probably perivenous) which contain glutamine synthetase (EC 6.3.1.2). Leucine kinetics, either for the whole body or splanchnic tissues, were not different between diets or level of ammonium salt infusion, except for oxidation which was less on the grass + barley ration. Amino acid concentrations were lower on the grass + barley diet but net PDV absorptions were similar. The pattern of essential amino acids absorbed into the PDV showed good agreement with the published composition of mixed rumen microbial protein. Fractional disappearances of absorbed free essential amino acids across the liver varied from 0.4 (branched chains) to near unity (histidine, phenylalanine).

Amino Acids↗
PubMed1996

Conversion of [15N]ammonia into urea and amino acids in humans and the effect of nutritional status.

Hepatic NH3 detoxification by ureagenesis requires an input of aspartate-N, originating either from amino acid-N or NH3-N. The relative importance of these two routes may depend on the nutritional state. To test this, four volunteers were given a liquid diet for 2 d and then on day 3 were either fed every 20 min or fasted. Doses of 15NH4Cl were taken orally every 20 min for 6 h (total 1.5 g) and blood was sampled hourly. Urea-N elimination under fasted conditions was only 0.75 of that for the fed state. Considering the increase in body urea pool during feeding, ureagenesis during fasting was probably closer to 0.6 of that during feeding. Since the [14N15N]urea enrichment was not different between the fed and fasted states, the proportion of the 15NH3 dose converted to urea during fasting was also 0.6 of that during the fed condition. No change in [14N15N]urea and [amide-15N]glutamine enrichment suggested that NH3 enrichment was also not affected by nutritional state. Enrichment of [15N15N]urea was approximately 0.05 that of [14N15N]urea which indicates that 15NH3 can also enter the aspartate route, the importance of which is yet unknown. Both [15N15N]urea and [amino-15N]glutamine enrichment in the fasted state were approximately 1.7 times that in the fed state, indicating increased labelling of precursors and/or increased NH3 flux through the aspartate route. Glutamate, valine, leucine and isoleucine showed comparable increases in enrichment during fasting. Arginine enrichment was unaltered by nutritional state, but was lower than [14N15N]urea, indicating incomplete equilibration with the arginine pool in periportal hepatocytes. The present study indicates that hepatic NH3 detoxification may use the aspartate route, gaining importance in the fasted state. The majority of urea was supplied with only one N atom from NH3, thus provision of the other may have consequences for alternative substrates, in particular amino acids.

Adult↗
PubMed1995

Hepatic detoxification of ammonia in the ovine liver: possible consequences for amino acid catabolism.

The effects of either low (25 mumol/min) or high (235 mumol/min) infusion of NH4Cl into the mesenteric vein for 5 d were determined on O2 consumption plus urea and amino acid transfers across the portal-drained viscera (PDV) and liver of young sheep. Kinetic transfers were followed by use of 15NH4Cl for 10 h on the fifth day with simultaneous infusion of [1-13C]leucine to monitor amino acid oxidation. Neither PDV nor liver blood flow were affected by the additional NH3 loading, although at the higher rate there was a trend for increased liver O2 consumption. NH3-N extraction by the liver accounted for 64-70% of urea-N synthesis and at the lower infusion rate the additional N required could be more than accounted for by hepatic removal of free amino acids. At the higher rate of NH3 administration additional sources of N were apparently required to account fully for urea synthesis. Protein synthesis rates in the PDV and liver were unaffected by NH3 infusion but both whole-body (P < 0.05) and splanchnic tissue leucine oxidation were elevated at the higher rate of administration. Substantial synthesis of [15N]glutamine occurred across the liver, particularly with the greater NH3 supply, and enrichments exceeded considerably those of glutamate. The [15N]urea synthesized was predominantly as the single labelled, i.e. [14N15N], species. These various kinetic data are compatible with the action of ovine hepatic glutamate dehydrogenase (EC 1.4.1.2) in periportal hepatocytes in the direction favouring glutamate deamination. Glutamate synthesis and uptake is probably confined to the perivenous cells which do not synthesize urea.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1995

Whole-body protein turnover from leucine kinetics and the response to nutrition in human immunodeficiency virus infection.

Whole-body protein metabolism was investigated in human immunodeficiency virus (HIV) infection by primed constant infusion of L-[1-13C]leucine in 8 control and 22 HIV-infected subjects (8 stage II; 14 stage IV disease), in postabsorptive and fed states. Postabsorptive leucine flux was increased 25% in subjects with stage IV HiV infection vs that in control subjects (130 +/- 13 vs 103 +/- 10 mumol leucine.kg-1.h-1, P < 0.001); both leucine disposal by protein synthesis (111.6 +/- 12.1 vs 82.3 +/- 9.2, P < 0.001) and release by protein degradation (129.7 +/- 13.1 vs 103.4 +/- 10.2, P < 0.001) were increased. No difference in leucine balance or oxidation was found but fat oxidation was greater in subjects with HIV infection (61.1 +/- 13.0% of energy) than in control subjects (47.6 +/- 13.7% of energy, P < 0.025). Stage II subjects had intermediate values of leucine flux, not significantly different from those of control subjects. Provision of parenteral nutrition for 4 h increased leucine flux with a switch in leucine balance from net loss to net gain; this response was quantitatively similar in all groups. HIV infection increases whole-body protein turnover but does not quantitatively impair the acute anabolic response to intravenous nutrition.

Adult↗
PubMed1995

Calculation of the need for paediatric intensive care beds.

A study of paediatric intensive care usage and need was undertaken in the former English Northern region to define appropriate local provision in the light of apparently conflicting published evidence. It was hypothesised that daily bed need would follow a Poisson distribution. All admissions of children aged less than 15 years who required intensive care in the region were recorded retrospectively for the financial year 1993/4. The mean number of beds occupied was 11.7 per day, which is equivalent to 20.7 beds per million children per day. The distribution of numbers of beds used mirrored a Poisson distribution closely, and the predicted bed requirement to cover 95% of days in the year was in agreement with that observed. Review of recommendations for paediatric intensive care provision from other studies suggests that apparent differences arise largely from the effect of different sizes of population served, and that, when allowance is made for this, underlying rates of bed requirement are strikingly similar, with a mean of around 20 per million children per day. A formula is given for the application of this model to local populations.

Adolescent↗
PubMed1994

The influence of exercise on the energy requirements of adult males in the UK.

Energy expenditure was measured over 10 d using the doubly-labelled water (DLW) and activity diary methods in summer and winter in subjects with 'light' occupations but leisure activities which ranged from 'non-active' to 'very active'. The basal metabolic rate (BMR) and the energy cost of activities were determined by indirect calorimetry. The Department of Health (1991) predicted BMR for the group (6.89 (SD 0.30) MJ/d; n 18) was not significantly different from the measured value (7.17 (SD 0.70) MJ/d; n 18). The range of DLW-derived expenditure values within the group was BMR x 1.41 to 2.41. The largest seasonal change within individuals was BMR x 0.5. The energy expenditure of the group as a whole was lower in winter (BMR x 1.88; SD 0.33; n 9) than summer (BMR x 2.01; SD 0.30; n 9) though the difference was not statistically significant. The average summer and winter DLW-derived expenditure was BMR x 1.96 (SD 0.31; n 17). The activity diary estimate of expenditure was BMR x 1.79 (SD 0.32; n 17). In a subset of the group who were representative of the most active 26% of all adult males in the UK, the DLW-derived expenditure was BMR x 2.08 (SD 0.24; n 11). This is higher than the highest Department of Health (1991) estimate of BMR x 1.6 for individuals in light occupations. The measured energy costs of low-intensity activities were similar to those presented in the Department of Health (1991) report but the value determined for running (BMR x 13.08; SD 2.4; n 6) was higher than the highest value in the report (BMR x 6 to 8). The results indicate that the recent Department of Health (1991) reference values for energy may underestimate the expenditure of a significant proportion of the UK population largely because the energy costs of activity used in the report to calculate expenditure do not accurately reflect those achieved during active leisure in individuals who take regular exercise.

Adult↗
PubMed1994

Protein synthesis in splanchnic tissues of sheep offered two levels of intake.

Protein synthesis rates were measured in liver and gastrointestinal tract (GIT) sections of fattening sheep offered lucerne (Medicago sativa) pellets at either 1.25 or 2 times energy maintenance. The measurement technique involved a large dose of [1-13C]valine over 60 min. Animals on the higher intake had a larger mass of liver protein (143 v. 100 g, P = 0.02), similar fractional synthesis rates (ks; 22.5 v. 22.1%/d, not significant) and greater absolute amounts of protein synthesis (32 v. 23 g/d; P = 0.016) compared with those on the smaller amount of ration. The ks values and RNA: protein in the GIT sections also tended to increase with food intake. Estimated total GIT protein synthesis was approximately three-fold that in liver and probably constituted 25-35% of whole body synthesis. All splanchnic tissues measured had lower translational efficiencies (g protein synthesized/d per g total RNA) than reported for milk-fed and newly-weaned lambs and this may relate to the decline in the rate of protein deposition as lambs progress to the fattening condition.

Amino Acids↗
PubMed1994

The effect of acute and chronic administration of the beta-agonist, cimaterol, on protein synthesis in ovine skin and muscle.

The action of intravenous infusion of the beta-agonist cimaterol (2.5 mg/d) on whole-body N retention and protein synthesis in peripheral tissues was examined in growing sheep. Wool growth was determined from skin patch clippings and adjusted to total fibre production. Protein synthesis was measured, using sequential large dose injections of [1-13C]valine, leucine and phenylalanine and then [ring-d5]phenylalanine, on biopsy samples from skin and m. longissimus dorsi taken before beta-agonist administration, at day 3 and day 15 of cimaterol infusion, and 15 d after withdrawal of the drug. Cimaterol increased total N retention by 1.9-2.3 g N/d (P < 0.01) over three successive 5 d periods. In contrast, wool growth was significantly reduced by 0.7 g N/d (P < 0.001) and the proportion of total N retained in wool declined from 0.71 to 0.25 (P < 0.01). The reduction in wool growth was accompanied by a decrease in protein fractional synthesis rate (FSR) in skin (11.6 v. 6.3%/d, P < 0.01). Muscle protein FSR, on the other hand, was markedly stimulated during cimaterol infusion (1.45 v. 3.01%/d, P < 0.001) as was RNA concentration (P < 0.001), RNA:protein (P < 0.001) and protein:DNA (P < 0.05). The estimated increase in total protein synthesis in muscle (+24 to 30 g/d) due to cimaterol administration was counterbalanced by reductions for skin (-25 to 27 g/d); this may account for the lack of changes in whole-body protein synthesis following beta-agonist administration reported in other studies. Although N retention rapidly returned to control values following withdrawal of the drug, both wool growth and skin protein synthesis remained depressed, while muscle protein FSR declined, but not to pre-treatment values. These results suggest a persistent action of cimaterol, but whether this is a function of residue concentrations or long-term metabolic responses is not known.

Adrenergic beta-Agonists↗
PubMed1994

An evaluation of ambulatory visit groups in rheumatology out-patients.

The development of case mix measures for National Health Service (NHS) care has become of great importance recently. Much effort has been put into devising measures for in-patient care, but measures for ambulatory (outpatient, day care and primary care) visits are less developed. Ambulatory Visit Groups (AVGs) is an American system devised to aggregate ambulatory visits into iso-resource groups. However, some assumptions made in the construction of the AVG system may not hold for the UK health service, including the use of consultation time as a proxy for the total resource use associated with the out-patient attendance. To test AVGs in the UK context, a three-month prospective study of rheumatology out-patient attendances at two hospitals in Newcastle upon Tyne assembled a database of 3393 'visits', together with resource use data. The AVGs derived from these were analysed to evaluate the homogeneity of the groups with respect to consultation resource use, and the degree to which consultation time can be considered a proxy for resource use in this setting. Consultation time distributions were markedly skewed, and required log transformation before analysis. Variation in log consultation time was found to depend as much on the clinician as on the AVG, and the two were observed to interact. Resource use distributions were also skewed, and were similarly transformed for analysis. Non-parametric analysis of variance showed resource use to be significantly associated with AVG, but the amount of variation associated with the AVG appeared to be small and inconsistent.(ABSTRACT TRUNCATED AT 250 WORDS)

Ambulatory Care↗
PubMed1994

Out-patient case mix: a survey of user requirements.

Research and development of out-patient case mix systems, to plan and monitor resource use in the out-patient sector, has hitherto not been accorded priority in the NHS. As part of an investigation of their usefulness, a survey of NHS professionals' requirements for out-patient case mix was conducted. The results confirmed that there was support for developing out-patient case mix systems, although different users had different requirements. However, a common theme to emerge was the desirability of constructing holistic systems which cover in-patient, day-case and out-patient care. Additionally, development of care packages was seen as a necessary first step in constructing systems for out-patient care. Concludes that visit-based case mix systems are unlikely to fulfil users' requirements and recommends that case mix contracting projects by Healthcare Resource Groups should be extended to the out-patient sector, but must recognize that existing systems do not meet users' requirements.

Ambulatory Care↗
PubMed1994

Validation in sheep of the doubly labeled water method for estimating CO2 production.

Carbon dioxide production (rCO2) was estimated in four sheep over a period of 10 days using doubly labeled water (2H and 18O) and was compared with simultaneous respiration chamber measurements of CO2. The excess 2H and 18O measurements were corrected for the empirically determined effects of isotope rebreathing within the confines of the chambers. A weighted monoexponential curve was then fitted to the data from which isotope flux rates and ultimately rCO2 and water turnover (rH2O) estimates were made. The curve fits were weighted assuming a Poisson model. Selection of this weighting policy did not bias the results, and curvature in the data also appeared to have little effect on the rCO2 estimates. Fractionated evaporative water loss expressed as a fraction of rH2O (X) was estimated from water balance and breath water production estimates; the mean X was 0.145 and ranged from 0.108 to 0.183. Corrections for 2H loss in fecal solids reduced the mean rH2O (4,746 g/day) by 35.5 g/day and increased the mean rCO2 (332.3 l/day) by 21.2 l/day. Further corrections to account for 2H loss in methane (mean production rate 27.2 l/day) reduced rH2O by 33.8 g/day and increased rCO2 by 20.3 l/day. The final isotopic estimates of rH2O were 14.6 +/- 6.59% (n = 4) lower than direct measurements and the mean rCO2 was 3.5 +/- 14.48% (n = 4) lower than the chamber measured rCO2. However, in one of the animals studied the rCO2 deviated markedly from the chamber-derived value, and this discrepancy has yet to be explained. When this animal was excluded from the comparisons, the standard deviation was greatly reduced (+/- 3.6, n = 3) and the mean overall error on rCO2 was +3.6%.

Animals↗
PubMed1994

Validation of the doubly labeled water method in growing pigs.

The CO2 production (rCO2) of eight growing pigs was determined by continuous collection of CO2 over 21 days and simultaneously estimated using the doubly labeled water (DLW) method. The aim was to assess the accuracy of the method before and after correction for known sources of error and to test for any residual discrepancy arising from as yet unidentified sources of error. Mass spectrometer accuracy was verified by analyzing serial dilutions of the dose material in the form of an artificial decay curve; no significant bias was detected. The physiological errors were linearly dependent on weight gain. DLW-derived rCO2 (corrected only for fractionated water loss) underestimated the true value by 0.270 l CO2/g wt gain or -8% in the restricted (group R) and -16% in the ad libitum-fed (group AL) groups. Known sources of error accounted for -0.006 (methane), -0.032 (fecal 2H losses), -0.108 (fat synthesis), and -0.146 (changing pool size) l CO2/g wt gain. After correction for these sources of error the DLW-derived rCO2 differed from the true value by -2 +/- 3% in group R and 0 +/- 3% in group AL. Thus there was no significant bias in the DLW method after correction for known sources of error, even during rapid weight gain or at weight stability with or without correction. The precision estimates include both dose and background errors and uncertainty in the correction factors used. Strategies for optimizing precision are presented.

Animals↗
PubMed1993

An absence of structural changes in the proximal femur with osteoporosis.

The hypothesis that osteoporosis occurs not as a preferential loss of the tensile trabeculae but as a general loss of bone was tested by using bone mineral densitometry and an indentation test on dissected proximal femora. As osteoporosis advanced a significantly correlated decrease was found in both bone mineral density and mechanical properties between the principal compressive and tensile trabeculae. The decrease correlated with a decrease in the Singh index. These findings led to the conclusion that a sequential bone loss from the tensile trabeculae to the compressive ones did not occur as Singh reported, but instead a generalized loss of bone mineral in both the tensile and compressive trabeculae supervened. The structural changes, on which the grading system by Singh was based, were not observed in the proximal femur affected by osteoporosis.

Aged↗