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Biomedical subjects

A J Matthews

Publications and source records attributed to A J Matthews.

15 recordsLinked to original sources
PubMed1998

Body posture during simulated tracheal intubation.

Seventeen experienced anaesthetists and 15 novices were filmed intubating the trachea of a training manikin. Measurements were made of the distance from manikin's chin to subject's nose and of the angles at the elbow, the shoulder and of the forearm with the horizontal. Trained subjects stood further back (trained: median 43 cm, interquartile range 41-56 cm; novices 35 cm, 26-38 cm; Mann-Whitney U, p < 0.01), with a straighter arm (trained elbow angle: 108 degrees, 99-121 degrees; novices': 92 degrees, 88-102 degrees; Mann-Whitney U, p < 0.01). Trained subjects tended to hold the laryngoscope closer to the hinge, with a pincer grip; novices were more likely to use a full grip of the handle. Trainers should consider giving novices explicit instructions on how to stand and how to hold the laryngoscope.

Anesthesiology↗
PubMed1997

Iron and atherosclerosis: inhibition by the iron chelator deferiprone (L1).

BACKGROUND: Accumulating evidence suggests that oxidative modification of lipoproteins may play a significant role in atherogenesis. In this study, we hypothesized that the iron chelator deferiprone (L1) would function as an antioxidant and decrease atherosclerosis progression. MATERIALS AND METHODS: For the in vitro studies, human low-density lipoprotein (LDL) was collected and then subjected to oxidation by either hemin/H2O2 or copper sulfate in the presence of various concentrations of L1. Lag time to oxidation was measured to assess antioxidant activity of L1. In addition, human umbilical vein endothelial cells (HUVEC) were subjected to oxidized LDL in the presence of varying concentrations of L1 to assess the antioxidant cytoprotective ability of L1. For the in vivo studies, rabbits (n = 21) were maintained on a 0.25% by weight cholesterol diet for 10 weeks; 9 rabbits also received twice daily L1 by gavage (total dose = 100 mg/kg/day). Lipid profiles were measured during the study. At 10 weeks, rabbits were sacrificed, and thoracic aorta cholesterol content (TACC) and planimetry were determined to assess atherosclerosis severity. RESULTS: In vitro, L1 prevented oxidation of LDL and protected HUVEC from the cytotoxic effects of oxidized LDL in a concentration-dependent manner. In vivo, L1 reduced TACC (P = 0.001), while also significantly decreasing total plasma cholesterol (P = 0.003), very-low-density lipoprotein cholesterol (P = 0.01), and LDL cholesterol (P = 0.002) compared to control animals. However, no significant differences between L1-treated animals and controls were evident for the surface area of plaque involvement by planimetry (P = 0.3) or in the serum iron levels (P = 0.3). CONCLUSIONS: These results confirm that L1 possesses antioxidant activity in vitro and may reduce atherogenesis in vivo.

Animals↗
PubMed1997

Lack of effect of vitamin E on cholesteryl ester transfer and lipoprotein composition in cholesterol-fed rabbits.

The concentration and activity of cholesteryl ester transfer protein (CETP) is increased in plasma in hypercholesterolemic humans and in experimental animals fed cholesterol. While the concentration of lipo-proteins appears to be the major determinant of CETP activity, we have found previously that dietary measures and pharmacologic agents that alter their lipid composition reduce the activity of CETP in plasma (CET). Since vitamin E is lipophilic and is incorporated into lipoproteins, we have examined the question of whether it too attenuates CET in cholesterol-fed New Zealand White rabbits prior to and 14 weeks after treatment with differing doses (5, 15, 30, 45 mg/kg) of vitamin E. Plasma triglycerides (TG), cholesterol (TC) and phospholipids (Lys, Sph, Lec, PI, PE) all increased significantly to a comparable degree in the rabbits fed cholesterol compared to those fed chow (p < 0.05; p < 0.01); the levels achieved were similar in the vitamin E-treated and untreated groups. As was observed with plasma lipids, cholesteryl ester transfer (CET) was accelerated to the same degree in each of the cholesterol-fed groups independent of whether they received vitamin E compared to chow-fed controls (p < 0.01) and the distribution of cholesterol in apo-B containing lipoproteins (VLDL, IDL, and LDL) was similar in the vitamin E-treated and untreated groups. These findings indicate that vitamin E has no discernible effect on CET when cholesterol levels are markedly elevated.

Animals↗
PubMed1984

Acid-base control during hypothermia. Acid-base control in children during hypothermia without temperature correction of pH and PCO2.

In 28 children undergoing cardiopulmonary bypass with deep hypothermia for open heart surgery, an attempt was made to maintain pH at 7.4 not corrected for temperature by varying the CO2 concentration supplied to the oxygenator so that the PaCO2 was 5.33 kPa, not corrected for temperature. One to two percent CO2 gave satisfactory results. Five percent CO2 had previously been given. No adverse clinical side effects were noted, and the acid-base status remained stable for 24 hours in 16 patients. There are strong theoretical reasons for maintaining a pH of 7.4, uncorrected for temperature, during hypothermia and a clinical impression was gained of better myocardial function and improved systemic and cerebral perfusion.

Acid-Base Equilibrium↗