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Biomedical subjects

G Lister

Publications and source records attributed to G Lister.

At least 37 records · Page 2Linked to original sources
PubMed1995

Microcirculatory response to surgical trauma in composite-tissue transfer.

A rat cremaster muscle-flap model for direct in vivo microcirculatory studies was combined with a rat hind-limb amputation/replantation model, to evaluate changes related to transfer trauma. Forty-eight inbred Sprague-Dawley rats were studied in two experimental groups. In a control group, the cremaster muscle was dissected as an island tube flap, transposed into the hind limb, and anchored at ankle level. No amputation was performed. In a second composite-limb-cremaster-graft group, the limb, with the inserted cremaster muscle flap, was amputated at mid-thigh level, and transferred to a recipient animal. In both groups, at follow-up periods of 1, 24, 48, and 72 hr, the cremaster flap was withdrawn from the limb and prepared for microcirculatory studies. The following parameters were measured: vessel diameters, RBC velocities, capillary density, and leukocytes in the postcapillary venules. Arteriolar and venular diameters, as well as RBC velocity values, were comparable in both groups. However, the composite isografts presented 50 percent more leukocytes sticking to the lumen of the postcapillary venules (p < 0.05) immediately following transfer. In addition, a significant decrease (12 percent) in the number of perfused capillaries was observed in the composite grafts throughout 72 hr. In this study on composite tissue transfer, trauma alone compromised the microcirculatory integrity of the tissue and proved to act as an independent factor. This should be considered during allotransplantations, where the addition of a rejection factor can further compromise graft survival.

Animals↗
PubMed1995

Maternal smoking and blood pressure in 7.5 to 8 year old offspring.

Reduced fetal growth in babies born preterm may be associated with reduced later blood pressure, but in children born at term, higher blood pressure. It was hypothesised, therefore, that maternal smoking in pregnancy, associated with reduced fetal growth, programmes later blood pressure differentially according to length of gestation. Six hundred and eighteen children born preterm and now aged 7.5 to 8 years were studied prospectively. Systolic blood pressure in children from smoking compared with non-smoking mothers was significantly lower in those born before 33 weeks' gestation and significantly higher in those born at 33 or more weeks. Within the range 0-40 cigarettes per day until delivery (after adjusting for potentially confounding factors, including social class and current weight) each 10 was associated with a 1.5 mm Hg fall and 2.9 mm Hg rise in pressure for children born below or above 33 weeks' gestation respectively. Similar though smaller differences were seen in diastolic pressure. These data support our hypothesis that later effects of insults impairing fetal growth are gestation dependent, and provide the first evidence that maternal smoking may have long term consequences for blood pressure in children.

Blood Pressure↗
PubMed1994

Effect of muscle flap denervation on flow hemodynamics: a new model for chronic in vivo studies.

The purpose of this study was to evaluate microcirculatory dynamics following muscle flap denervation. A modification of standard cremaster muscle flap was used. Fifty male Sprague-Dawley rats were studied in two experimental groups of 25 rats each, as follows: Group I (control), after flap isolation, the neurovascular pedicle was left intact; group II (denervation), following muscle isolation at 1 cm segment of genitofemoral nerve was excised and denervated muscle was preserved in the medial border of rat hind limb. For chronic evaluation the cremaster was withdrawn from the leg and prepared for in vivo observations after days 1, 3, 7, and 14. The following measurements were taken: vessel diameters, red blood cell velocities, and number of perfused capillaries. In group II a 15% increase in arteriolar diameter was observed. Throughout the entire 14 day period denervated flaps presented 27% more perfused capillaries. Flap denervation proved to increase capillary perfusion significantly (P < 0.05). The cremaster muscle tube-flap model introduced in this study allows for chronic observation of the microcirculation.

Animals↗
PubMed1994

Size at birth and later blood pressure.

Adults who were small at birth have been reported to have higher systolic blood pressure and risk of ischaemic heart disease in later life. Conversely, in 616 subjects of less than 34 weeks' gestation and 1850 g birth weight, systolic and diastolic blood pressures at 7.5 to 8 years of age decreased with decreasing weight for gestational age and were not related to birth weight. These data do not support the view that fetal growth retardation before 34 weeks programmes for increased blood pressure in later life.

Blood Pressure↗
PubMed1993

Arterial anatomy of the thumb.

The anatomical literature has indicated that the arterial supply to the thumb comes from the princeps pollicis artery. However, this simplified description does not often correlate with intraoperative findings. The purpose of this study was to investigate and clarify this important area of anatomy by dissection of fresh cadaver hands. 40 dissections were completed on 35 intravascularly injected and five non-injected hands. Five patterns were identified. The most common pattern showed both a superficial and deep vessel to the first web space in 54% of specimens. Dominant vessels included the superficial palmar branch of the radial artery in 8%, first palmar metacarpal artery in 18% and dorsal metacarpal artery in 8%. Only three specimens correlated with the textbook description. We conclude that the term "princeps pollicis" is actually a misnomer.

Arteries↗
PubMed1993

Leukocyte-depleting effect of hypothermia on muscle flap microcirculation following ischemia-reperfusion injury.

The aim of this study was to determine the effect of leukocyte-endothelial interaction and capillary perfusion on the microcirculation of muscle flaps submitted to ischemia in normothermic and hypothermic conditions. The cremaster muscle flap model was employed. Sixty rats were studied in six groups: normothermic and hypothermic control groups and groups that underwent reperfusion after 4 and 6 hours of ischemia in both normothermic and hypothermic conditions. In each group the following measurements were made: main vessel diameters, red blood cell velocities, the number of perfused capillaries, and the number of leukocytes rolling and sticking in the postcapillary venules. Hypothermia decreased the flow rate significantly and eliminated leukocytes from the microcirculation. Six hours of ischemia under normothermic conditions proved to be lethal for these muscle flaps, whereas hypothermia preserved flap viability.

Animals↗
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↗