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Biomedical subjects

A MacDonald

Publications and source records attributed to A MacDonald.

At least 91 records · Page 5Linked to original sources
PubMed1997

Gastric emptying in patients with constipation following childbirth and due to idiopathic slow transit.

BACKGROUND: Idiopathic slow transit constipation (ISTC) is considered to be a heterogeneous condition in which patients have varying sites and degrees of delayed gastrointestinal transit. The majority of patients have pancolonic disease, and colectomy with ileocolorectal anastomosis has been the mainstay of surgical treatment. Severe constipation following traumatic childbirth is now being recognized and this subgroup of patients may have delayed transit confined to the rectosigmoid colon. In theory, proximal transit in these patients should be normal. METHODS: Gastric emptying was studied in patients with constipation following childbirth or ISTC and in controls. After an overnight fast, both patients and controls received breakfast, which consisted of cornflakes, sugar and milk. The liquid marker 111In-labelled di-ethylene tri-amine penta-acetic acid (DTPA) was added to the milk. A solid marker, 99mTc-labelled colloid, was impregnated on to paper and sealed with cellulose. The t1/2 for gastric emptying was calculated. RESULTS: Liquid phase emptying was normal in both constipation following childbirth and ISTC. Solid phase emptying was delayed significantly in ISTC compared with that in patients with constipation following childbirth and controls. In addition, half the patients with ISTC had delayed transit through the small bowel and proximal colon. Small bowel and colonic transit were normal in patients with constipation following childbirth. CONCLUSION: Patients with constipation following childbirth represent a distinct subgroup with normal proximal gastrointestinal function. Gastric emptying studies may be helpful in selecting patients for surgical management of severe constipation.

Adult↗
PubMed1996

Effects of catecholamines on isolated human colonic smooth muscle.

1. The effects of catecholamines and some adrenoceptor agonists and antagonists on isolated preparations of human colonic smooth muscle obtained from surgical resections were examined. 2. Strips of circular smooth muscle displayed rhythmic myogenic spontaneous contractions which were inhibited by catecholamines with an order of potency of isoprenaline (1.0) > noradrenaline (0.32) > adrenaline (0.2). Phentolamine (0.7 microM) significantly shifted the noradrenaline concentration-response curve (CRC) to the right but had no significant effect on isoprenaline or adrenaline. Propranolol (1 microM) significantly shifted the isoprenaline to the right but had no significant effect on noradrenaline or adrenaline. 3. Salbutamol (30 microM) had no inhibitory effect on the spontaneous activity and ICI 118,551 (1 microM) had no effect on inhibitory responses to isoprenaline. Betaxolol (1 microM) significantly shifted the CRC to isoprenaline to the right. BRL 37344 had no effect on spontaneous activity. 4. Responsiveness of circular strips to catecholamines was not affected by age of the patient and no consistent differences between males and females were shown. 5. Strips of taenia coli exhibited little or no spontaneous phasic activity. Noradrenaline and isoprenaline relaxed KCl-induced tone. The effects of noradrenaline and isoprenaline were antagonized by propranolol but not by phentolamine. BRL 37344 had no effect on KCl-induced tone. 6. In conclusion, catecholamines relaxed spontaneous activity of human colon circular smooth muscle through an action on both alpha- and beta-adrenoceptors. The alpha-adrenoceptors were of the alpha 1-subtype. The beta-adrenoceptor-mediated relaxation appeared to be primarily beta 1. In taenia coli, catecholamines relaxed KCl-induced tone via beta-adrenoceptors only.

Adrenergic alpha-Agonists↗
PubMed1996

Nutritional management of cystic fibrosis.

Nutritional support is an integral part of the management of cystic fibrosis patients. It is arguably best provided by a qualified dietitian and nutritional care sister working in conjunction with the rest of the cystic fibrosis team. The patient's nutritional needs should be assessed, regularly reviewed, and nutritional treatment tailored to meet the changing clinical and psychosocial needs of the patient. Nutritional intervention is not without complications, and in particular attention to normal feeding behaviour and vigilance when instituting supplementary nutrition may prevent many feeding difficulties.

Adolescent↗
PubMed1996

Factors affecting the variation in plasma phenylalanine in patients with phenylketonuria on diet.

The optimal dietary management of children with phenylketonuria (PKU) has rarely been rigorously explored. The aim of this study was to assess longitudinally the effects of three factors thought to influence plasma phenylalanine concentrations in PKU: total energy intake; protein intake from natural foods allowed freely in addition to allocated phenylalanine exchanges; and the distribution of protein substitute throughout the day. Nineteen subjects, 15 girls and four boys aged 1-16 years, were enrolled. Food intake was weighed, and twice daily plasma phenylalanine concentrations measured during either 3-day or 4-day periods, for a total of 21 days throughout six months. There was a negative correlation between the percentage of protein substitute eaten by the time of the evening meal and the fall in plasma phenylalanine concentration during the day (r = -0.941; p < 0.0001). On average, 49% of pre-evening meal plasma phenylalanine concentrations were less than 100 mumol/l in children who had taken at least 65% of their protein substitute by the time of their evening meal. There was no correlation between excess natural protein intake from freely allowed foods and (a) pre-breakfast or pre-evening meal plasma phenylalanine concentrations or (b) the daily change between pre-breakfast and pre-evening meal concentrations. Nor was there any correlation between excess natural protein intake on the previous day and plasma phenylalanine concentration on the following morning. Energy intake was not correlated with plasma phenylalanine concentrations. It is therefore preferable to distribute the protein substitute evenly through the day in order to achieve stable phenylalanine concentrations, rather than to carry out further fine manipulation of the phenylalanine intake, which would make management of the diet even more difficult.

Adolescent↗
PubMed1996

Prevention of anaemia in inner city toddlers by an iron supplemented cows' milk formula.

There are few data to support the use of follow-on formulas in infants from the age of 6 months. In a prospective trial in a deprived inner city area of Birmingham 100 infants who were already receiving pasteurised cows' milk by 6 months of age were enrolled and randomised either to receive a follow-on formula or to continue on cows' milk from 6 months until 18 months. At 18 months of age the follow-on formula group returned to cows' milk and both groups were followed up until 24 months. Iron status, growth, and nutritional status were analysed at intervals of six months. At enrollment, no differences in haematological status were evident. However, by 12 months of age, 31% of the cows' milk group were anaemic (haemoglobin concentration < 110 g/l) compared with only 3% of those receiving follow-on formulas. At 18 months, 33% of the cows' milk group were anaemic compared with only 2% of the follow-on formula group and by 24 months of age none of the follow-on formula group was anaemic, whereas 26% in the cows' milk group still had a haemoglobin of < 110 g/l. Mean corpuscular volume was significantly smaller and ferritin significantly lower in the cows' milk group at 12, 18, and 24 months. Dietary iron intake was higher in the follow-on formula group at 12 and 18 months but not at 24 months, when both groups were back on cows' milk. Infants and toddlers at high risk of iron deficiency are therefore unlikely to become anaemic if receiving a follow-on formula, although the relative merits of follow-on formula compared with an ordinary infant formula remain uncertain.

Anemia, Iron-Deficiency↗
PubMed1996

Pedicle screw instrumentation for unstable thoracolumbar fractures.

We evaluated the results of short-segment pedicle screw instrumentation in 54 patients with unstable thoracolumbar fractures. Follow-up averaged 25 months (range, 11 to 36 months); 42 patients completed the study. Kyphosis was corrected by an average of 7 degrees at surgery and loss of correction averaged 5 degrees at the end of follow-up. On computed tomography, canal compromise averaged 57% preoperatively and 33% postoperatively. Complications included nerve root irritation due to screw penetration (1/42), screw breakage (2/42), and screw bending (6/42). Solid fusion was achieved in all cases at an average of 3 months. Of the 31 patients with normal neurologic function, 24 (77%) were pain-free at follow-up and had returned to previous levels of activity. We conclude that short-segment fixation with posterolateral fusion is effective in the treatment of unstable thoracolumbar fractures; it prevents progression of kyphotic deformity and neurologic deterioration, results in a stable fusion, and preserves uninvolved motion segments above and below the fracture site.

Adult↗
PubMed1995

Contributions of beta-adrenoceptor subtypes to responses to isoprenaline in rat isolated distal colon.

The effects of the non-selective beta-adrenoceptor antagonist propranolol and the beta 1- and beta 2-adrenoceptor-selective antagonists, respectively CGP 20712A (((+/-)-[2-(3-carbamoyl-4-hydroxyphenoxy)-ethylamino]-3-[4-(1-meth yl-4- trifluoromethyl-2-imidazolyl)-phenoxy]-2-propanol hydrochloride)) and ICI 118,551 ((erythro(+/-)-1-(7-methylindan-4-yloxy)-3-isopropylamino butan-2-ol- hydrochloride)), on isoprenaline-induced inhibition of methacholine contractions in rat distal colon were investigated to determine the contributions of beta-adrenoceptor subtypes to relaxation of smooth muscle. Longitudinal segments of rat distal colon were suspended in Krebs solution at 37 degrees C for isometric recording. The Krebs solution contained EDTA (30 microM), ascorbic acid (30 microM) and prazosin (0.1 microM) and was gassed with 95% O2-5% CO2. Isoprenaline produced a concentration-dependent inhibition of methacholine-induced contractions. Propranolol produced a small (4-6-fold) significant shift of the isoprenaline concentration-response curve at 0.003-0.01 microM. Larger shifts were produced by 0.3 microM (13-fold) and 1 microM (20-fold). CGP 20712A produced a small (3-5-fold) significant shift at 0.03-1 microM. ICI 118,551 produced small non-significant shifts (2-3-fold) at 0.03-1 microM. A combination of ICI 118,551 (0.3 microM) and CGP 20712A (0.1 microM) produced a 13-fold shift, a significantly greater shift than expected from the individual shifts. The shift produced by the combination of antagonists was slightly less than that produced by 1 microM propranolol (20-fold).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Clinical examination compared with anthropometry in evaluating nutritional status.

Clinical assessments of nutritional status in a group of 44 inpatients, made by a panel of experienced childcare specialists, were compared with anthropometric assessments. Assessors were uniformly poor at detecting severe malnutrition and at assessing the nutritional status of infants. Nutritional status cannot be accurately assessed clinically and anthropometry is crucial.

Anthropometry↗
PubMed1995

Comparison of an elemental with a hydrolysed whey formula in intolerance to cows' milk.

In a double blind study, 40 infants with cows' milk intolerance of various causes were randomised to receive a nutritionally complete formula in which nitrogen was supplied either as whey hydrolysate or amino acids. The median age of infants was 10 weeks (range 36 weeks' gestation to 108 weeks' postnatal age). After a median follow up period of 25 weeks there was no significant difference in dietary intake between the formulas. Twenty four weeks after entry, weight and weight for length improved equally on both formulas. Plasma albumin improved significantly on the hydrolysed whey formula but not in the amino acid group. Both milks were palatable and normal intakes of formula were maintained. Biochemical and haematological indices remained within normal limits. There was no difference in stool frequency and vomiting between the two formulas. Two infants developed a probable allergic colitis while receiving hydrolysed whey. Amino acid formula may have a role in the management of atopic infants with severe cows' milk intolerance who have already reacted to whey or casein hydrolysate formula.

Amino Acids↗
PubMed1995

Which formula in cow's milk protein intolerance? The dietitian's dilemma.

During the last century a wide range of protein sources have been used to replace cow's milk to provide an alternative milk in the treatment of cow's milk protein intolerance. These include soya (Businco et al., 1992), ass's milk (Iacono et al., 1992), soya/beef hydrolysate (Dean et al., 1993), almonds (Moll, 1923), poppy seeds (Findelstein 1930), cereals (Wolpe & Silverstone, 1942), whey hydrolysate (Walker-Smith, Digeon & Phillips, 1989) casein hydrolysate (Walker-Smith et al., 1989) and taro (Feingold, 1942). Important factors influencing the choice of milk substitute include nutritional composition, evidence of successful use with particular reference to satisfactory growth and nutritional status, palatablility, ease of preparation, cost, availability and allergenicity.

Dietetics↗
PubMed1994

Evaluation of an apatite cement as a root end filling material.

A self-setting apatite cement, EBA cement, and amalgam with varnish were tested for root end sealing ability using a fluid filtration and dye technique. Single-rooted human teeth were prepared in vitro to receive root end fillings. Experimental groups were amalgam with two layers of varnish, EBA cement with dry cavity, EBA cement within a wet cavity, apatite cement within a dry cavity, and apatite cement within a wet cavity. Fluid filtration measurements were made at 6, 24, and 7 days, and 1 and 3 months. Each specimen was also subjected to a dye leakage test using Procion Green dye at 3 months. Results indicated that apatite cement provided a comparable seal to amalgam and EBA cement. This finding, in conjunction with its excellent biocompatibility, suggests that apatite cement is an acceptable alternative to present-day root end filling materials.

Aluminum Oxide↗