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R P Stevens

Publications and source records attributed to R P Stevens.

9 recordsLinked to original sources
PubMed1991

Recovery of neuromuscular function during reperfusion of the ischemic extremity: effect of mannitol and superoxide dismutase.

The ability of mannitol and superoxide dismutase (SOD) to improve the recovery of peripheral nerve and skeletal muscle function and to influence metabolism during reperfusion after 4 hours of complete ischemia was investigated in an autoperfused canine hind-limb model. Study groups included control subjects (n = 7), subjects given 5000 units/kg of SOD intra-arterial bolus immediately before reperfusion and 10,000 units/kg infusion during first hour of reperfusion (n = 7), and subjects given 150 mg/kg isosmolar mannitol intra-arterial bolus before reperfusion and 1 gm/kg intravenous infusion during the first hour of reperfusion. Function was evaluated by determining isometric twitch and tetanic contractile force of paw dorsiflexion by stimulating the peroneal nerve or the anterior tibial muscle. Metabolic responses (oxygen consumption and lactate clearance) and blood flow were not influenced by either treatment protocol. However, mannitol significantly reduced muscle damage and significantly improved neuromuscular contractile function compared to control and SOD treatment regimens.

Analysis of Variance↗
PubMed1982

Bronchoscopic location of bronchopleural fistula with xenon-133.

Successful application of the technique of transbronchoscopic endobronchial occlusion of a persistent bronchopleural fistula requires an accurate determination of the segmental location of the air leak. This was achieved by injections of small boluses of Xe-133 into a number of segmental bronchi through a fiber-optic bronchoscope. Following the instillation of Xe-133 into the segmental bronchus leading to the fistula, there was a marked increase in radioactivity in the intercostal drainage tube.

Aged↗
PubMedDate not supplied

Contractile and metabolic function following an ischemia-reperfusion injury in skeletal muscle: influence of oxygen free radical scavengers.

Skeletal muscle contraction and metabolism was evaluated using an in vivo, intact autoperfused canine hindlimb model during 7 hours of reperfusion following 4 hours of complete ischemia, with and without bolus administration of superoxide dismutase (SOD) and catalase (CAT) at the start of reperfusion. Contractile tension of paw dorsiflexion during reperfusion demonstrated small but statistically non-significant increases of recovery towards pre-ischemic baseline with SOD/CAT (i.e. 43% +/- 10 vs 32% +/- 9 with muscle-stimulated tetanic tension). Oxygen utilization by the hindlimb rose during reperfusion from a baseline in the control group of 2.4 +/- 0.3 ml 02/min to 5.4 +/- 1.1 during the first 10 minutes and plateaued at 3.5 +/- 1.3 by the first hour with no differences in the SOD/CAT group. Lactate clearance was prompt (increase from a pre-ischemia value of zero to 0.93 +/- .14 mM/min by 5 minutes and return to near-zero by 1 hour in controls) exhibiting no sustained anaerobic metabolism and was not affected by SOD/CAT. These finding demonstrate irreversible loss of 60-70% of skeletal muscle contraction with preservation of aerobic metabolic capacity at 225% of basal activity. Bolus administration of SOD/CAT at the start of reperfusion offered no significant improvement in metabolic or contractile function. These observations, in a model simulating the in vivo setting, necessitate evaluating alternate ischemia reperfusion conditions and modified free-radical inhibitor protocols before any clinical benefit can be assumed.

Animals↗