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Biomedical subjects

G Lister

Publications and source records attributed to G Lister.

At least 19 recordsLinked to original sources
PubMed1992

Breast milk and subsequent intelligence quotient in children born preterm.

There is considerable controversy over whether nutrition in early life has a long-term influence on neurodevelopment. We have shown previously that, in preterm infants, mother's choice to provide breast milk was associated with higher developmental scores at 18 months. We now report data on intelligence quotient (IQ) in the same children seen at 7 1/2-8 years. IQ was assessed in 300 children with an abbreviated version of the Weschler Intelligence Scale for Children (revised Anglicised). Children who had consumed mother's milk in the early weeks of life had a significantly higher IQ at 7 1/2-8 years than did those who received no maternal milk. An 8.3 point advantage (over half a standard deviation) in IQ remained even after adjustment for differences between groups in mother's education and social class (p less than 0.0001). This advantage was associated with being fed mother's milk by tube rather than with the process of breastfeeding. There was a dose-response relation between the proportion of mother's milk in the diet and subsequent IQ. Children whose mothers chose to provide milk but failed to do so had the same IQ as those whose mothers elected not to provide breast milk. Although these results could be explained by differences between groups in parenting skills or genetic potential (even after adjustment for social and educational factors), our data point to a beneficial effect of human milk on neurodevelopment.

Age Factors↗
PubMed1992

Oxygen transport during anemic hypoxia in pigs: effects of digoxin on metabolism.

We tested whether digoxin would limit tissue hypoxia during severe anemia by improving peripheral O2 distribution or decreasing O2 demands. Hematocrit (Hct) was reduced in eight control and eight digoxin-treated pigs from 27-28% to 17-18, 11-12, and 7-8%. Whole body and hindlimb blood flow, O2 transport, O2 extraction, and O2 consumption and serum catecholamines (epinephrine and norepinephrine) were determined at each Hct. Arterial and femoral venous lactate and O2 deficit were obtained to reflect tissue hypoxia. Cardiac output was significantly greater (P less than 0.05) with digoxin, as expected, but there were no differences in hindlimb blood flow. Also, whole body and hindlimb O2 extractions were equal in both groups for similar levels of O2 transport, suggesting that digoxin did not alter the relationship of O2 flow to metabolism in regional circulations. As whole body O2 consumption fell, controls accumulated more (P less than 0.05) O2 deficit and arterial lactate than the digoxin group. Furthermore, the slope demonstrating the linear increase of lactate with respect to O2 deficit was much steeper in controls (y = 1.11 + 0.06x) than in digoxin (y = 1.36 + 0.02x), suggesting that there were differences in the degree of tissue hypoxia for comparable O2 deficit. This may be attributed to the marked differences in catecholamine response: epinephrine was higher in controls at Hct of 7-8% and norepinephrine was higher at Hcts of 11-12 and 7-8%. Digoxin may have inhibited the release of catecholamine or reduced the stimulus for catecholamine secretion during anemia. We speculate that digoxin markedly improved the balance between peripheral O2 supply and demand during anemia by inhibiting catecholamine thermogenesis, thereby decreasing O2 demands. This may explain some of the salutary effects of glycosides in high-output cardiac failure with normal ventricular function.

Anemia↗
PubMed1992

The pronator quadratus muscle flap: coverage of the osteotomized radius following elevation of the radial forearm flap.

Skin-graft take following elevation of the osteocutaneous radial forearm flap has been shown to be difficult. The pronator quadratus muscle flap can be elevated to cover the exposed osteotomized radius and flexor carpi radialis and brachioradialis tendons. This technique is technically easy to perform and may significantly reduce donor-site wound-healing problems.

Adult↗
PubMed1991

Musculus lumbricalis pollicis.

In six cases of thumb hypoplasia, a muscle arose from the anomalous flexor pollicis longus tendon in the region of the metacarpophalangeal joint, passed across the narrowed first web space, joined the lumbrical belly of the index, and inserted into the extensor hood of that digit. Traction on the muscle at its origin in the thumb produced extension of the interphalangeal joints of the index finger. Because of its attachments and action, this muscle has been given the name musculus lumbricalis pollicis. Not previously described in this form, the muscle is significant in hypoplasia because its contraction will act to narrow the already deficient first web space. In all instances where it was present, the musculus lumbricalis pollicis was excised.

Humans↗
PubMed1991

Pollex abductus in hypoplasia and duplication of the thumb.

Pollex abductus is an anomaly in which the flexor pollicis longus attaches not only at its customary insertion, but also into the extensor by a tendon that passes around the radial aspect of the thumb. Contraction of the anomalous flexor abducts the thumb. In the original report, the anomaly occurred in thumb hypoplasia. A similar anomaly is reported in 11 hypoplastic thumbs (35.5% of all cases) and in 9 cases of radial polydactyly (21.4%). The common feature was poor definition of the interphalangeal skin crease, with complete absence of active flexion of that joint. All patients were treated surgically; 13 before the age of 10 months, with correction of the duplication and the hypoplasia, and in the latter with elimination of the abduction deformity and restoration of opposition. The anomalous connection was excised in all patients. Active interphalangeal joint motion after reconstruction of the hypoplastic thumbs averaged 21 degrees.

Adolescent↗
PubMed1991

Functional assessment of pulmonary capillary surface area in the 2-mo-old lamb.

We recently reported that measurements of the maximal velocity of pulmonary endothelial angiotensin-converting enzyme (Vmax) in vivo provide information regarding microvascular surface area in the developing lamb. To obviate any subtle influences of development on Vmax aside from simple increases in surface area, we correlated Vmax with postmortem stereological assessments of alveolar surface area in the relatively mature lung of the 2-mo-old lamb (n = 14). We attempted to increase the range of surface area beyond its normal variability by injecting nine of the lambs with bleomycin, an antineoplastic agent with significant pulmonary toxicity in other species. Vmax, measured shortly after birth and then weekly, increased monotonically in all lambs. Despite their wide dispersion, Vmax and the stereological determinations correlated strongly at 2 mo of age, confirming that Vmax is a robust indicator of the surface area of the air-blood barrier. There was no significant difference in either measurement between the control lambs and those treated with bleomycin, suggesting that the newborn lamb is resistant to the effect of this agent.

Age Factors↗
PubMed1990

Results of primary tendon repair with closure of the tendon sheath.

This study reports the results of primary flexor tendon repair combined with closure of the tendon sheath in 31 Zone 2 injuries. In 3 digits, the profundus tendon alone was divided. In a further 7 digits, one tendon was completely divided and the other was incompletely divided. The remaining 21 digits involved complete division of both tendons. Assessment of the results according to the total active motion (TAM) system found 86% of the repairs in the excellent, good and fair categories. Two ruptures occurred (6%). A second assessment employed the criteria of Strickland, excluding the motion of the metacarpophalangeal joint. The results obtained following suture of both tendons were: excellent (39%); good (36%); fair (14%); poor (4%); and rupture (7%). These results lend support to the belief that closure of the tendon sheath decreases external adhesion formation and improves motion without increasing the risks of rupture.

Adult↗
PubMed1989

Hypertension and asthma: psychological aspects.

Essential hypertensive and asthmatic patients, plus normal non-clinical controls, were compared on a number of psychological measures in order to identify the relationship between psychological distress, coping strategies and compliance behaviour. The hypothesised relationship between chronic clinical ailments and psychological distress was confirmed. The association between the presence of physical symptoms in the symptomatic condition, asthma, and greater psychological distress was also confirmed. The coping strategies adopted by the patients did not discriminate between the two clinical groups. Compliance with medication was negatively correlated with measures of psychological distress. Compliance with an appropriate healthy lifestyle was not correlated with medication compliance, although it too was negatively correlated with other measures of psychological distress.

Adaptation, Psychological↗
PubMed1989

Effect of hemoglobin concentration on critical cardiac output and oxygen transport.

We previously found limited tolerance to acute reduction in cardiac output in lambs at the nadir of their physiological anemia [Am. J. Physiol. 253 (Heart Cir. Physiol. 12): H100-H106, 1987]. To determine the effect of hemoglobin concentration [Hb] on critical cardiac output, critical systemic O2 transport, and peripheral O2 extraction, we performed 31 experiments in 12 one-mo-old lambs at four [Hb] (means +/- SD in g/dl): 7.4 +/- 0.6, 10.5 +/- 0.5, 14.5 +/- 0.5, and 16.5 +/- 0.6. Desired [Hb] was obtained by exchange transfusion with packed red cells or plasma. Cardiac output was reduced by inflation of a balloon-tipped catheter in the right atrium, and critical levels were defined at the point where O2 consumption decreased and/or arterial blood lactate concentration increased in response. With lower [Hb], cardiac output was unchanged, systemic O2 transport was reduced, and fractional O2 extraction was increased, keeping O2 consumption constant at base line. As [Hb] was reduced, critical cardiac output was significantly higher, whereas critical systemic O2 transport was independent of [Hb], as were fractional O2 extraction and mixed venous PO2 at the critical point. Thus peripheral O2 extraction was not affected by changes in [Hb] during progressive decreases in cardiac output. We conclude that 4-wk-old lambs have decreased tolerance to reductions in cardiac output and systemic O2 transport because their relative anemia provides them with a base-line cardiac output and systemic O2 transport close to the critical level.

Animals↗
PubMed1989

Response to low cardiac output: developmental differences in metabolism during oxygen deficit and recovery in lambs.

When cardiac output is critically lowered, whole body O2 consumption decreases and an O2 deficit accumulates. With restoration of cardiac output, an excess O2 consumption is expected in order to "repay" some or all of the O2 deficit. We tested the hypothesis that young lambs, with higher resting O2 consumption, cardiac output and growth rates than older lambs, would repay less of their O2 deficit because they have a higher proportion of nonessential metabolism. We reduced cardiac output acutely by inflating a Foley catheter in the right atrium of spontaneously breathing, sedated lambs at ages 2 (n = 5) and 8 (n = 5) wk. Each lamb was studied with low cardiac output periods of 30 and 60 min on different days. Aortic and pulmonary artery blood pressures, gases, and O2 saturations, venous Hb, and arterial lactate concentrations were measured every 10 min during baseline, low output, and 60 min of recovery. Oxygen consumption was monitored continuously. Oxygen deficit and excess O2 of recovery were calculated from the time integral of the difference between O2 consumption at baseline and during the respective study period. The average percent decreases in cardiac output (66.4 and 64.6%) and O2 consumption (38.1 and 35.1%) were similar in the 2- and 8-wk groups, respectively. There was no consistent relation between O2 deficit and O2 repayment in either age group. However, on average the 2-wk group repaid a significantly lower percentage (3 +/- 16%, mean +/- SEM) than 8-wk-olds (76 +/- 29%).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1989

Interpretation of metabolic function of the lung. Influence of perfusion, kinetics, and injury.

Quantitative assessment of pulmonary metabolic function has been shown to be a novel and important approach to obtaining specific and subtle biochemical information regarding endothelial cell function in the normal and diseased lung. A primary consideration in this measurement of whole organ metabolism, whether it be enzyme, transport, or binding functions, it is to be able to separate convective from kinetic aspects of endothelial cell physiology. Significant progress has been made in both our understanding of the influence of convective factors, as well as of possible solutions relying on mixed order kinetics. Nonetheless, the pervasive influence of surface area on these metabolic measurements and the distinct likelihood that this variable is simultaneously altered with endothelial cell function in acute lung injury makes definitive statements premature at this time. Several approaches to resolve this important issue have been attempted and include simultaneous measurement of nonmetabolic endothelial cell function including DLCO or permeability to urea; simultaneous measure of microvascular space for water or antipyrine; comparison with complex uptake and binding of a lipophilic basic amine such as propranolol; and multiple metabolic markers that may be selectively affected by injury. Other advances that should prove useful include an on-line computer registration of metabolic information, as well as gamma-scintigraphy for the purpose of obtaining regional information.

Animals↗
PubMed1989

Perioperative care of the infant with congenital heart disease.

The current approach to the perioperative management of the infant and child with congenital heart disease has been discussed. The major focus has been on potential problems of oxygen transport as they relate to vital organ system function. Management strategies for specific defects or perioperative problems have also been considered as well as the newer on-line monitoring techniques, while stressing the importance of careful clinical evaluation. The ultimate surgical outcome is dependent not only on the adequacy of repair or palliation but on the treatment of potential life-threatening situations that may take place during the critical postoperative period.

Heart Defects, Congenital↗
PubMed1988

Postnatal growth of the sheep lung: a morphometric study.

Stereologic methods were used to study lung development in sheep from 2 to 171 days of age. Most growth occurs within the first 2 months when there is a threefold increase in lung volume, but allometric relationships show that this increase does not keep pace with body weight. Alveolar and capillary surface areas increase as lung volume to a power only slightly larger than 1, suggesting a modest increase in complexity; this is confirmed by only a two- to threefold increase in total alveolar number. Allometric power functions are essentially unchanged even during the first 30 days so that throughout development, the surface for gas exchange is added at a fairly constant rate. A slight increase in septal volume during the first 30 days is probably due to relative increase in capillary luminal volume through a progressive distension of capillaries. The results suggest that the active newborn lamb requires an alveolar lung, but in the postnatal period functional needs increase only moderately. In contrast, other mammals, such as the rat, are helpless as newborns and have a primitive saccular lung that must undergo considerable morphogenesis to meet the demands of the active adult.

Animals↗
PubMed1988

Post-operative management of flexor tendon grafting.

This paper reviews the post-operative management of 145 tendon grafts in 127 patients. 80 grafts were managed post-operatively by a period (three to four weeks) of immobilisation followed by gentle active mobilisation. 65 grafts were managed by immediate controlled mobilisation (Kleinert technique) for three to four weeks. The final motion obtained was independent of the post-operative management. However, the rates of graft rupture (nine against four) and of tenolysis (sixteen against eight) were higher in the immobilised group.

Female↗