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Biomedical subjects

R W Logan

Publications and source records attributed to R W Logan.

At least 19 recordsLinked to original sources
PubMed1999

Infant cerebellar gray and white matter fatty acids in relation to age and diet.

There is little evidence as to the fatty acid composition of the cerebellum in infancy and it remains uncertain whether milk diet can influence its composition. We therefore examined cerebellar gray and white matter of infants less than 6 month old who had died unexpectedly. The fatty acid content of 33 gray and 21 white matter specimens from infants born at term and 6 gray and 5 white matter specimens from preterm infants was assessed by gas chromatographic/mass spectrometric analysis. Infants were grouped according to whether they had received human or manufactured formula milk. Whereas cerebellar cortex docosahexaenoic acid (DHA, 22:6n-3) concentrations were significantly lower (P<0.01) in the formula-fed than breast-fed infants, no differences existed between the term (n = 10) and preterm (n = 5) Synthetic Milk Adapted [corrected] (SMA) formula-fed infants. Cerebellar white matter DHA concentrations were similarly lower (P<0.01) in the SMA formula-fed infants (n = 8) than in an age-matched breast-fed group. Low concentrations of cerebellar white matter lignoceric (24:0) and nervonic acid (24:1n-9) in two 7-wk-old preterm infants appeared to correlate with postgestational rather than chronological age. Dietary long-chain polyunsaturated fatty acids, particularly DHA, are probably essential for normal development of the infant cerebellum.

Aging↗
PubMed1999

Endothelin-1 levels in infants with pulmonary hypertension receiving extracorporeal membrane oxygenation.

We studied the possibility of an etiological role for endothelin-1 (ET-1) in the development of persistent pulmonary hypertension of the newborn (PPHN). Ten infants with severe PPHN requiring extracorporeal membrane oxygenation (ECMO) were studied. Pre and post pulmonary blood samples were obtained on commencing ECMO and on recovery. The samples were analyzed by radio-immunoassay. The infants with PPHN requiring ECMO had a significantly higher mean ET-1 concentration (21.1 pmol/l, S. D. 3.59) than a group of healthy controls (16.6 pmol/l, S. D. 4.44); however 8 of our 10 infants had individual ET-1 levels within our reference range for healthy newborns. Pre and post pulmonary ET-1 levels did not differ significantly and there was no evidence of a decline in ET-1 levels with resolution of PPHN. Pulmonary overproduction of ET-1 does not appear to be the cause of PPHN, although the endothelin system may still play a role in the pathophysiology of PPHN, probably mediated through changes in receptor expression.

Carotid Arteries↗
PubMed1998

Salicylate toxicity masquerading as malignant hyperthermia.

We report a case of hyperpyrexia presumed due to topical salicylate toxicity occurring immediately following general anaesthesia for appendicectomy in an eleven year old boy. Some of the features strongly suggested the diagnosis of malignant hyperpyrexia.

Administration, Topical↗
PubMed1998

Infant growth and aorta total lipid fatty acids.

Abnormal fetal and infant growth have increasingly been correlated with adult onset cardiovascular disease. To date, there is little known about the lipid fatty acid profiles in infant cardiovascular tissue. Therefore, we analysed total lipid fatty acids from thoracic and abdominal aorta intima and media from 24 normally grown sudden infant death syndrome cases. Aorta from small for gestational age (n = 2), failure to thrive from birth (n = 3), and premature (n = 1) infants were also examined. Dihomo-gamma-linolenic acid (C20:3n-6) and oleic acid (C18:1n-9) concentrations were significantly lower in the thoracic than in the abdominal aorta. Similar dietary related differences were found in the subgroup (n = 15) of infants fed on formula milks. Both abdominal and thoracic intimal arachidonic (C20:4n-6) to dihomo-gamma-linolenic acid ratios were greater in the infants with retarded growth after birth than in their normally grown counterparts. Growth restriction in infancy might disrupt the normal accretion of vascular endothelial polyunsaturated fatty acids.

8,11,14-Eicosatrienoic Acid↗
PubMed1998

Transient 5-oxoprolinuria (pyroglutamic aciduria) with systemic acidosis in an adult receiving antibiotic therapy.

5-Oxoprolinuria is a recognized condition with increased urinary excretion of 5-oxoproline and is associated with a variety of inborn metabolic defects involving the series of enzyme-linked reactions known as the gamma-glutamyl cycle. We report the unusual case of a 35-year-old woman who initially presented with staphylococcal pneumonia but went on to develop a transient high anion gap metabolic acidosis. The development and subsequent complete recovery from this acidosis were subsequently shown to be related in time to the intravenous administration of the antibiotics flucloxacillin and netilmicin. Analysis of the patient's urine for organic acids revealed massively increased excretions of 5-oxoproline at the peak of her acidosis. We suggest that this patient developed a transient disturbance in the gamma-glutamyl cycle involving the 5-oxoprolinase step, which resulted in accumulation of 5-oxoproline that caused a severe high anion gap metabolic acidosis. The administered antibiotics remain as possible causative agents.

Acidosis↗
PubMed1996

Synthesis and characterisation of acyl glycines. Their measurement in single blood spots by gas chromatography-mass spectrometry to diagnose inborn errors of metabolism.

Acyl glycines are normally minor metabolites of fatty acids; however, the excretion of certain acyl glycines is increased in several inborn errors of metabolism. Therefore measurement of the metabolites in body fluids can be used to diagnose these metabolic disorders. The chemical synthesis of a range of acyl glycines is described, together with that of their 13C2-isotopomers for use as internal standards. An analytical method for the measurement of hexanoyl, octanoyl, 3-phenylpropionyl and suberyl glycines in urine, employing gas chromatography-mass spectrometry with negative-ion chemical ionisation was adapted to measure a larger range of acyl glycines in a single blood spot on a standard Guthrie card. Diagnoses of a case of medium-chain acyl-CoA dehydrogenase deficiency and a case of isovaleric acidaemia were confirmed using a single blood spot from each patient.

Calibration↗
PubMed1996

Hypomagnesaemic tetany.

Hypomagnesaemic tetany (hypomagnesaemic tetany with secondary hypocalcaemia) is a rare inherited form of hypomagnesaemia. Initial reports involved affected males only; however, affected females have also been reported. The case of a child with hypomagnesaemic tetany is described, the biochemical and genetic aspects of this condition are reviewed and the importance of the assessment of renal magnesium excretion in patients presenting with hypomagnesaemia is highlighted.

Child, Preschool↗
PubMed1996

The acute phase response to cardiopulmonary bypass in children.

The endocrine phase of the stress response to cardiopulmonary bypass in children is known to be subtly different from that seen in adults. The aim of this investigation was to determine whether there are similar differences in the acute phase response. Thirteen children were studied (mean age 2.65 years). Each child had congenital heart disease and underwent corrective cardiac surgery. Blood samples taken two days prior to operation and at 6, 9, 12, 24, 48 and 120 hours after were analysed for C-reactive protein, albumin, caeruloplasmin, zinc and copper concentrations. Metal:carrier protein molar ratios were also calculated. Results demonstrate changes which, although similar to those seen in adults, differed both quantitatively and qualitatively. This is explained by the concept of immaturity leading to a generally poor capacity for protein synthesis and a relative inability to respond to altered circumstances.

Acute-Phase Reaction↗
PubMed1996

Acute-phase responses to cardiopulmonary bypass in children weighing less than 10 kilograms.

BACKGROUND: Cardiopulmonary bypass induces a systemic inflammatory response. This study investigated, in a pediatric population, cytokine-induced responses and their potential modification by intraoperative steroid administration. METHODS: Markers of the acute-phase response were measured perioperatively in 24 children weighing less than 10 kg undergoing cardiac operations. Those having operations with cardiopulmonary bypass were randomized to receive either no steroid (group I, n = 8) or 10 mg/kg methylprednisolone in the pump prime (group II, n = 10); patients undergoing nonbypass procedures were controls (group III, n = 6). RESULTS: In all groups, plasma interleukin-6 level was elevated (p < 0.01) above baseline throughout the post-operative period, peaking earlier in group I. Levels of C-reactive protein peaked at 48 hours, and postoperative core temperature was raised in all groups. Levels of interleukin-6 from 2 to 6 hours and C-reactive protein at 24 hours postoperatively were greater (p < 0.05) in group I than in group II. Maximum interleukin-6 level, C-reactive protein level, and temperature were all significantly greater in group I than in group III. Maximum interleukin-6 level correlated with maximum C-reactive protein level in group I only (rs = 0.76; p < 0.05) and showed no association with temperature. Duration of bypass did not correlate with levels of interleukin-6. CONCLUSIONS: This study demonstrated a marked acute-phase response to operation; the greater response to procedures with cardiopulmonary bypass was abrogated by intraoperative steroid administration. The importance of interleukin-6 as an inducer of acute phase proteins after bypass is supported by its association with C-reactive protein levels, but other factors must be important in the induction of pyrexia.

Acute-Phase Reaction↗
PubMed1995

Effect of diet on the fatty acid composition of the major phospholipids of infant cerebral cortex.

The fatty acid compositions of the major cerebral cortex phospholipids, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine were measured in 16 term and one preterm 'cot death' infants fed exclusively either breast milk or one of two formulas. Docosahexaenoic acid (DHA; C22:6n-3) content in cerebral cortex phosphatidylethanolamine and phosphatidylserine of breast fed infants was greater than in both formula groups with significances varying between p < 0.1 and p < 0.001. Compensation for this deficiency in DHA in the formula fed infants was largely achieved by increased incorporation of docosapentaenoic acid (C22:5n-6) in the cerebral cortex of term infants and Mead (C20:3n-9) and dihomo Mead acids (C22:3n-9) in the preterm infant. As the phospholipids most affected are known to perform an important role in membrane function and are possibly integral to neurotransmission it is recommended that breast milk substitute infant formulas should contain n-3 and n-6 series polyunsaturated fatty acids in proportions similar to those of human milk.

8,11,14-Eicosatrienoic Acid↗
PubMed1995

Nutritional status of children with congenital heart disease.

OBJECTIVE: To assess the nutritional status of children with congenital heart disease. DESIGN: Six anthropometric, 24 biochemical, and five haematological markers of nutritional wellbeing were measured in children with congenital heart disease. SETTING: The west of Scotland. PATIENTS: 48 children admitted consecutively for surgical correction of congenital heart disease. MAIN OUTCOME MEASURES: Height, weight, and triceps and subscapular skin fold thicknesses were considered abnormal if they were below the third centile compared with standard reference data for age matched British children. Mid-arm circumference and arm muscle circumference were considered abnormal if they fell below the fifth centile compared with standard data. Biochemical and haematological data were compared with age matched and locally validated laboratory normals. RESULTS: A marked degree of undernutrition was evident in all children; 52% had weight less than the third centile, 37% were below the third centile for height, and 12.5% were below the third centile for triceps skin fold thickness and 18.8% for subscapular skin fold thickness. Mid-arm circumference and arm muscle circumference were below the fifth centile in 20.1% and 16.7% of children respectively. Five or more of the 29 biochemical and haematological measurements were abnormal in 83.3% of patients; 10 or more were abnormal in 12.5% of patients. CONCLUSIONS: Children with congenital heart disease are frequently undernourished, irrespective of the nature of cardiac defect and the presence or absence of cyanosis.

Arm↗
PubMed1995

Age- and dietary-related distributions of hepatic arachidonic and docosahexaenoic acid in early infancy.

A dietary-related deficiency of docosahexaenoic acid [C22:6(n-3)] in infant cerebral cortex has been identified. Absence or very low rates of hepatic synthesis from the essential fatty acid precursor, alpha-linolenic acid [C18:3(n-3)], in early life may have been a contributory factor. We have analyzed liver total lipid fatty acid compositions in 27 term (37-42 wk gestation) and 4 preterm (30-33 wk gestation) infants who died within the first 6 mo of life from sudden infant death syndrome. The infants were fed exclusively either human or formula milks. Formula-fed infants were subdivided into two groups, one receiving SMA milk with an alpha-linolenic acid content at 1.5% of total fatty acids and the other a composite group fed milks with low alpha-linolenic acid concentrations (< 0.1% to 0.4%). The hepatic content of arachidonic acid [C20:4(n-6)] and docosahexaenoic acid was generally lower in both formula-fed groups than in the human milk-fed group. The age-related distributions of docosahexaenoic acid showed that coincident minimum levels were present in both formula groups in the third month of life. This may indicate that the hepatic enzymes involved in the final stage (delta 4-desaturation) conversion of alpha-linolenic acid to docosahexaenoic acid could be inactive in the first months of life. Emphasis must be on provision of preformed dietary docosahexaenoic acid and possibly arachidonic acid as well as their essential fatty acid precursors, to both term and preterm infants for at least the first 16 wk of life.

Animals↗
PubMed1994

Neonatal endothelin-1 concentrations in term infants.

Endothelin-1 concentrations were studied in 30 term infants during the first week of life using a radioimmunoassay kit. A neonatal reference range was established (7.5-25.7 pmol/l). No significant relation with age, sex, gestation, or birth weight was found.

Endothelins↗
PubMed1993

Comparison of metabolic responses to laparoscopic and minilaparotomy cholecystectomy.

This randomized study compared the metabolic responses to laparoscopic cholecystectomy (n = 10) and minilaparotomy cholecystectomy with a 5-7-cm incision (n = 10). Venous blood samples were taken before operation and at 3, 6, 9, 12, 18, 24, 48, 72 and 168 h after incision and analysed for levels of C-reactive protein, interleukin 6, cortisol, albumin, transferrin, iron, fibrinogen, fibrin degradation products and polymorphonuclear elastase, and for neutrophil and lymphocyte counts. Urine samples (24 h) were analysed for urea, creatinine, 3-methylhistidine and catecholamines. The magnitude of the metabolic changes from baseline levels was quantified by calculating areas under each individual curve. A significant metabolic response with a similar time course and magnitude of changes occurred after laparoscopic and minilaparotomy cholecystectomy but with wide variation in magnitude between individuals.

Adult↗
PubMed1993

Malonyl coenzyme A decarboxylase deficiency.

Two new cases of malonyl coenzyme A (CoA) decarboxylase deficiency are described. Hitherto, the worldwide experience of the disorder has been confined to reports on two affected Australian children. The new cases are Scots born and are the offspring of consanguinous parents of Scots/Irish origin. They were investigated during episodes of vomiting and febrile convulsions associated with concomitant developmental delay. Malonic aciduria and grossly reduced malonyl CoA decarboxylase activity were demonstrated and the total ion current chromatograms of urinary organic acid profiles obtained by gas chromatography-mass spectrometry are presented. The clinical and biochemical features of the Scots and Australian patients are compared.

Adipates↗