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Biomedical subjects

A MacDonald

Publications and source records attributed to A MacDonald.

At least 73 records · Page 4Linked to original sources
PubMed1999

Identification of patients to include in trauma audit: a modification of the pre-chart.

Trauma audit is commonly focused using a Pre-Chart to illustrate calculations made using the TRISS model. A line is drawn at Ps = 0.5 to divide expected survivors and nonsurvivors. The use of this cut-off in a severely injured population was examined. The 'M statistic' for a group of injured patients selectively triaged to a Trauma Centre was calculated. The ideal cut-off point between predicted outcomes when using the TRISS model to focus trauma audit in this population was determined using a Receiver Operating Characteristic (ROC) curve. For this population the TRISS 'M statistic' was 0.71 (indicating a significantly different case mix from the reference database) and the best cut-off point was at Ps = 0.76. Trauma audit in populations with a case mix of injury severity different from the reference database should use a different Ps line to define unexpected outcomes.

Humans↗
PubMed1999

Psychological characteristics of people with perceived food intolerance in a community sample.

In most adults who believe themselves to be food intolerant there is no objective supporting evidence. It has therefore been proposed that the misperception of intolerance to food is linked to psychiatric illness or personality disorder. This hypothesis was tested in a community-derived sample of individuals who attributed an adverse symptom to a type of food. A random mailing recruited 955 participants aged > or =18 years, of whom 232 perceived themselves to be food intolerant (PFI). All recruits were sent two questionnaires, the General Health Questionnaire-28 (GHQ-28) and the shortened version of the Eysenck Personality Questionnaire (EPQ-R). A total of 535 GHQ-28 and 518 EPQ-R forms were returned that were correctly completed, an overall response rate of 55%. For the subscales of the EPQ-R, neuroticism was greater in those with a PFI than those without. Women with a PFI were more extroverted than control women. For the GHQ-28 subscales, women with a PFI had significantly higher scores than control women on somatic symptoms, anxiety, insomnia, and severe depression. There was a greater percentage of psychiatric caseness among women with a PFI than among men with a PFI or control women. Nevertheless, this percentage was no greater than that reported among a reference sample derived from NHS and university staff. It is concluded that perceived food intolerance is associated with psychological distress in women with a PFI, and neurotic symptoms in both men and women with a PFI, but there is no greater prevalence of psychiatric disorder among women or men with a PFI than there is in some professional groups.

Adult↗
PubMed1999

Characterisation of the atypical beta-adrenoceptor in rabbit isolated jejunum using BRL 37344, cyanopindolol and SR 59230A.

The present study was carried out to further investigate the nature of the beta-adrenoceptor in rabbit jejunum using BRL 37344, a selective beta3-adrenoceptor agonist, cyanopindolol, a beta-adrenoceptor antagonist with blocking activity at beta3-adrenoceptors and SR 59230A, a new selective beta3-adrenoceptor antagonist. Isoprenaline produced a concentration-dependent inhibition of the spontaneous contractions of rabbit jejunum with a pD2 of 7.14. Propranolol (1 microM) shifted the isoprenaline concentration-response curve (CRC) to the right with a concentration-ratio of 5.85, considerably less than would be expected for an action at classical beta-adrenoceptors (estimated pA2 6.66). BRL 37344 also produced a concentration-dependent inhibition of spontaneous contractions with a pD2 of 7.41. The BRL 37344 CRC was unaffected by propranolol (1 microM). In the presence of propranolol (1 microM), cyanopindolol (1 microM) shifted the isoprenaline CRC to the right (concentration-ratio of 21). Cyanopindolol also shifted the BRL 37344 CRC to the right (concentration-ratio of 38). These shifts are consistent with the affinity of cyanopindolol for beta3-adrenoceptors (estimated pA2 values of 7.27 and 7.38 against isoprenaline and BRL 37344, respectively). In the presence of propranolol (1 microM), SR 59230A produced a concentration-dependent rightward shift of the isoprenaline CRC. The Schild plot gave a pA2 value of 7.16, although the slope of the regression line was significantly different from unity (0.65). SR 59230A also produced a concentration-dependent shift of the BRL 37344 CRC. The Schild plot gave a pA2 of 7.58 with the slope of the regression line not significantly different from unity (0.81). The presence of beta3-adrenoceptors mediating relaxation of spontaneous contractions in rabbit jejunum is supported by the relatively poor antagonism of isoprenaline by propranolol, the relaxant effect of BRL 37344 and the antagonism of isoprenaline and BRL 37344 by cyanopindolol and SR 59230A. The lack of simple competitive antagonism of isoprenaline, but not BRL 37344, by SR 59230A may suggest more than one population of atypical beta-adrenoceptor.

Adrenergic beta-Agonists↗
PubMed1999

Effects of propranolol and L-NAME on beta-adrenoceptor-mediated relaxation in rat carotid artery.

1. The properties of beta-adrenoceptors mediating vascular relaxation in rat isolated carotid artery were investigated. Ring segments of arteries were preconstricted with the thromboxane A2 receptor agonist U-46619 and relaxation to beta-adrenoceptor agonists determined. 2. Isoprenaline produced a concentration-dependent relaxation of U-44619-constricted arteries. The concentration-response curve (CRC) to isoprenaline was shifted to the right by propranolol (1 microM) although the shift was less (105 fold; pA2, 8.02) than would be expected for an effect of isoprenaline at classical beta-adrenoceptors (300-1000 fold; pA2, 8.5-9). L-NAME (100 microM) significantly reduced responses to isoprenaline, lowering the slope of the CRC and reducing the maximum response. 3. The selective beta3-adrenoceptor agonists, BRL 37344 and ZD2079, also produced concentration-dependent relaxation of the arteries. L-NAME (100 microM) shifted the BRL 37344 CRC to the right 15 fold with no reduction in the slope or maximum response. L-NAME (100 microM) had no significant effect on the ZD2079 CRC. 4. In conclusion, relaxation to isoprenaline in rat carotid artery is inhibited by propranolol in a manner suggesting a mixed population of classical (beta1-/beta2-) and atypical (beta3-) adrenoceptors. The presence of beta3-adrenoceptors was confirmed by the relaxant effects of the selective beta3-adrenoceptor agonists BRL 37344 and ZD2079. L-NAME attenuated responses to both isoprenaline and the beta3-adrenoceptor agonist BRL 37344, suggesting a role for endothelial release of nitric oxide in beta-adrenoceptor mediated relaxation. However, the relaxant effect of BRL 37344 was attenuated by L-NAME to a lesser extent than that of isoprenaline. In addition, L-NAME had no effect on relaxation induced by ZD2079. These results suggest that there may be a differential contribution of endothelium to classical beta-and beta3-adrenoceptor-mediated effects, with endothelium contributing less to beta3-adrenoceptor-mediated relaxation.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1999

V-shaped cushion at the origin of bovine pulmonary supernumerary arteries: structure and putative function.

This study investigates the anatomic structure at the origin of pulmonary supernumerary arteries and their parent conventional artery. Histological examination showed that at the origin of each supernumerary artery the wall of the parent conventional artery is organized into a distinct V-shaped structure, which begins on the hilum side of each supernumerary artery as a funnel-shaped channel running into the supernumerary artery. The base of the channel is particularly thin walled. The lateral walls of the channel are composed of musculoelastic cushions that become more pronounced toward the supernumerary artery and fuse on its distal side, forming a baffle that projects over the supernumerary artery lumen. These V-shaped structures/cushions were observed with video stereo dissecting microscopy in both an open and closed state in isolated arteries in vitro. Pulmonary vasoconstriction of isolated arteries with the thromboxane A(2) mimetic U-46619 increased the number of V-shaped structures in the closed state. These studies indicate the presence of a novel anatomic structure at the origin of pulmonary supernumerary arteries, which may be able to regulate blood flow into the supernumerary artery.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1998

Red cell membrane fatty acids, cytosolic phospholipase-A2 and schizophrenia.

Forty subjects with schizophrenia and 40 age- and sex-matched controls were recruited, and blood samples were obtained for analysis of red cell membrane fatty acid composition by capillary gas chromatography. A blood sample was also taken from the same population to test for allelic association between schizophrenia and a polymorphism close to the promoter site of the cytosolic phospholipase-A2 gene which is mapped to chromosome 1q25. The schizophrenic population was heterogeneous with regards age, symptoms severity and treatment. A significantly higher percentage concentration of dihomogamma-linolenic acid (DGLA) was found in the red cell membranes of schizophrenics compared to matched controls. All other fatty acids examined showed no difference from the normal population. No correlation was found between any demographic factor, treatment variable, diet, drug use, alcohol or tobacco consumption which could explain the biochemical findings. A negative correlation was found between the concentration of DGLA in red blood cell (RBC) membranes and severity of symptoms of schizophrenia. In particular, there was a significant correlation (r = -0.41, p = 0.009) between DGLA percentage concentrations and 'disorganised' symptoms. No association was found between schizophrenia and alleles of the polymorphism near the phospholipase-A2 gene or between fatty acid concentrations and the presence of any particular alleles. This study therefore finds support for membrane phospholipid abnormalities in patients with schizophrenia and particular symptom clusters, but does not replicate a previous report of an allelic association between a polymorphism close to the site of the cytosolic phospholipase-A2 gene and schizophrenia.

Adult↗
PubMed1998

Rhizopus microsporus in wooden tongue depressors: a major threat or minor inconvenience?

The investigation and management of an apparent outbreak of Rhizopus spp. in a London paediatric referral centre between September 1995 and April 1996 is described. The organism was identified in microbiological surveillance samples from 23 patients nursed in four hospital areas. Investigations revealed the presence of the organism in spatulae from all ward areas investigated and from closed boxed containers held in the central hospital stores obtained from a new supplier. In contrast, culture of spatulae from the initial supplier failed to yield any fungal isolates. The incident was reported to the Medical Device Agency (MDA), the Central Public Health Laboratory Service (CPHLS) and the Birmingham PHLS. A statement was prepared for the weekly Communicable Disease Report and a hazard warning issued by the MDA. The spatulae were withdrawn from use and the contract with the original supplier was re-established. This incident resulted in contamination of samples only and no patient involvement. It highlights the problems which may follow use of equipment for unintended purposes and the need for good manufacturing practice guidelines to be applied to non-sterile equipment used in direct patient care.

Child↗
PubMed1998

Does a single plasma phenylalanine predict quality of control in phenylketonuria?

A 1993 MRC working group on phenylketonuria suggested standardising blood phenylalanine measurements by taking blood samples at the same time each day. Since it is not known how representative of a 24 hour period a single phenylalanine concentration is, the aim of this study was to investigate the 24 hour variability of plasma phenylalanine in well controlled children with phenylketonuria. Sixteen subjects, 12 girls and four boys aged 1 to 18 years, had hourly venous blood samples collected for 13 hours between 09.00 and 21.00 on one day. Serial skin puncture blood specimens were then collected at 24.00, 03.00, and 06.00 within the same 24 hour period. All food and drink was weighed. The median variation in plasma phenylalanine concentration was 155 mumol/l/day, with a minimum of 80 and a maximum of 280. The highest concentration occurred in the morning between 6.00 and 9.00 in 63% of subjects; the lowest occurred between midday and midnight in 94%. Concentrations < 100 mumol/l occurred in 46% of children below 11 years, three having concentrations < 30 mumol/l for two, six, and seven hours respectively. Three of five subjects had concentrations above the MRC guidelines for 24% of the period studied. Except in two subjects, the blood concentrations did not rise in response to phenylalanine consumption. However, the greater the quantity of protein substitute taken between waking and the 16.00 specimen, the larger the decrease in daytime phenylalanine concentration (r = -0.7030) (p < 0.005). There is therefore wide variability in phenylalanine concentrations in a 24 hour period in children with phenylketonuria which is not reflected in a single observation. Further study is needed to investigate the effects of timing of protein substitute on the stability of phenylalanine concentrations.

Adolescent↗
PubMed1998

Reducing bacterial contamination of enteral feeds.

OBJECTIVE: It has previously been shown that microbial contamination of enteral feeds given to children in hospital and at home is common. This study therefore examined the effects of improvements in the enteral feeding protocol, coupled with an intensive staff training programme, on bacterial contamination. METHODS: The enteral feeding protocol was modified by: priming the feeding set on an alcohol treated metal tray, spraying the bottle opener and top with 70% alcohol, wearing non-sterile disposable gloves, and filling the feeding reservoir with feed for up to 24 hours' use rather than only four hours. Daily feeds samples were collected from 16 inpatients and home patients on enteral nutrition at the start and end of feeding. Seventy seven samples were cultured. Results were compared with previously published control data. RESULTS: Enteral feed contamination rates were reduced significantly from 62% to 6% of feeds given at home (p < 0.001), and from 45% to 4% of feeds given in hospital (p < 0.001). CONCLUSIONS: This study highlights the importance of using an appropriate enteral feeding protocol, and of regular staff training in reducing contamination rates of enteral feeds to an acceptable level.

Child, Preschool↗
PubMed1997

Ultrastructural Effects of a Non-Steroidal Ecdysone Agonist, RH-5992, on the Sixth Instar Larva of the Spruce Budworm, Choristoneura fumiferana.

Force feeding of RH-5992 (Tebufenozide), a non-steroidal ecdysone agonist to newly moulted sixth instar larvae of the spruce budworm, Choristoneura fumiferana, (Lepidoptera: Tortricidae) initiates a precocious, incomplete moult. Within 6h post treatment (pt) the larva stops feeding and remains quiescent. Around 12hpt, the head capsule slips partially revealing an untanned new head capsule that appears wrinkled and poorly formed. By 24hrpt, the head capsule slippage is pronounced and there is a mid-dorsal split of the old cuticle in the thoracic region but there is no ecdysis. The larva remains moribund in this state and ultimately dies of starvation and desiccation. The temporal sequence of the external and internal changes of the integument were studied using both scanning and transmission electron microscopy. Within 3hpt, there is hypertrophy of the Golgi complex indicating synthetic activity and soon after, large, putative ecdysial droplets are seen. Within 24h, a new cuticle that lacks the endocuticular lamellae is formed. The formation of the various cuticular components, the degradation of the old cuticle and changes in the organelles of the epidermal cells of the mesothoracic tergite are described. The difference between the natural moult and the one induced by RH-5992 are explained on the basis of molecular events that take place during the moulting cycle. The persistence of this ecdysone agonist in the tissues permits the expression of all the genes that are up-regulated by the presence of the natural hormone but those that are turned on in the absence of the hormone are not expressed.

Journal Article↗
PubMed1997

Evaluation of full-term infants fed an evaporated milk formula.

The objective of this prospective, cohort study was to compare the nutritional status of full-term infants who were fed human milk (BF, n = 29), formula (FF, n = 30) or evaporated milk formulae (EM, n = 30) for at least 3 months. Infants were seen at enrollment, 3 and 6 months, at which times a blood sample, diet record and anthropometric data were collected. Infants in the EM group received solids earlier (12 +/- 5 weeks) than did FF infants (15 +/- 4 weeks), and both were earlier than BF infants (19 +/- 4 weeks). Only 26% of the EM fed group received iron supplements as ferrous sulphate drops. Seven BF, 12 FF and 20 EM had abnormal ferritin values (< 10 ng ml-1) at 6 months. Copper intake was lower in the EM infants at 3 and 6 months. However, plasma copper and erythrocyte copper zinc superoxide dismutase (ZnCuSOD) levels did not differ between groups. Selenium intake was lower in the EM group (5 +/- 1 and 10 +/- 5 micrograms d-1; 3 and 6 months) than in the FF infants (13 +/- 4 and 19 +/- 7 micrograms d-1; 3 and 6 months). Erythrocyte SeGHSPx levels in EM infants were lower at 6 months (EM, 33.2 +/- 3.4; FF. 35.2 +/- 3.9: BF, 36.1 +/- 3.8 mU mg Hb-1). Thiamin intake (0.99 +/- 0.08 and 1.24 +/- 0.32; 3 and 6 months, mg 1000 kcal-1) was higher in the FF group than in EM infants (0.38 +/- 0.39 and 0.66 +/- 0.38; 3 and 6 months). There were more (13%) abnormal thiamin assays in the EM group at 6 months than in the BF and FF infants (0%). In conclusion, infants fed evaporated milk formula receive adequate copper but may not receive enough thiamin or selenium. Unless supplemented from birth with medicinal iron, intakes of iron will be inadequate.

Animals↗
PubMed1997

Enteral nutrition after bone marrow transplantation.

Nutritional insult after bone marrow transplantation (BMT) is complex and its nutritional management challenging. Enteral nutrition is cheaper and easier to provide than parenteral nutrition, but its tolerance and effectiveness in reversing nutritional depletion after BMT is poorly defined. Nutritional status, wellbeing, and nutritional biochemistry were prospectively assessed in 21 children (mean age 7.5 years; 14 boys) who received nasogastric feeding after BMT (mean duration 17 days) and in eight children (mean age 8 years, four boys) who refused enteral nutrition and who received dietetic advice only. Enteral nutrition was stopped prematurely in eight patients. Greater changes in weight and mid upper arm circumference were observed in the enteral nutrition group, while positive correlations were found between the duration of feeds and increase in weight and in mid upper arm circumference. Vomiting and diarrhoea had a similar incidence in the two groups, while fever and positive blood cultures occurred more frequently in the dietetic advice group. Diarrhoea occurring during enteral nutrition was not associated with fat malabsorption, while carbohydrate malabsorption was associated with rotavirus infection only. Enteral feeding did not, however, affect bone marrow recovery, hospital stay, general wellbeing, or serum albumin concentrations. Hypomagnesaemia, hypophosphataemia, zinc and selenium deficiency were common in both groups. In conclusion, enteral nutrition, when tolerated, is effective in limiting nutritional insult after BMT. With existing regimens nutritional biochemistry should be closely monitored in order to provide supplements when required.

Body Weight↗
PubMed1997

Acute mountain sickness is not altered by a high carbohydrate diet nor associated with elevated circulating cytokines.

We investigated whether a diet of increased carbohydrate content reduces the symptoms of acute mountain sickness (AMS) and whether concentrations of circulating cytokines rise and correlate with hypoxia and AMS. There were 19 healthy volunteers who ingested in randomized order both a high carbohydrate (68% CHO) or normal carbohydrate (45% CHO) diet for 4 d. On the 4th d, subjects were exposed to 8 h of 10% normobaric oxygen. Each subject completed the Lake Louise Consensus Questionnaire (LLCQ: a questionnaire developed to quantify the common symptoms and consequences of AMS) at the beginning and end of each hypoxic session, at which times venous blood was obtained for the following cytokines: interleukins 1 beta, 6 and 8 (IL-1 beta, IL-6, IL-8) and tumor necrosis factor alpha (TNF-alpha). AMS symptoms did not differ significantly between the diets (LLCQ scores: 68% CHO = 10.1 +/- 3.8 vs. 45% CHO = 10.3 +/- 4.1). Cytokine concentrations did not change with hypoxia on either diet, nor did individual changes correlate with AMS symptoms. We conclude that a high carbohydrate diet for 4 d does not reduce the symptoms of AMS; and plasma cytokine concentrations do not change with hypoxia and the development of AMS and, thus, are not likely mediators of this syndrome.

Acute Disease↗