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Biomedical subjects

C M Thorpe

Publications and source records attributed to C M Thorpe.

25 records · Page 2Linked to original sources
PubMed1994

Use of aprotinin in knee replacement surgery.

We have studied the effect of aprotinin on blood loss and subsequent blood transfusion in 17 patients undergoing knee replacement surgery. Patients receiving aprotinin (total dose 2,000,000 kallikrein inhibiting units) received fewer units of blood than control patients (P < 0.05), although there was no significant difference in blood loss between the two groups. The study was stopped when one patient in the aprotinin group needed an above-knee amputation because of ischaemia secondary to arteriovenous thrombosis after knee replacement surgery. Although the patient had peripheral vascular disease which could have accounted for the thrombosis, the role of aprotinin under tourniquet conditions is unclear.

Aged↗
PubMed1994

Air inlets for infusion bottles.

We assessed the resistance to air flow in four commonly used air inlets. The Avon A81 and Codan air inlets provide the least resistance to flow, followed by the Baxter CO413 and lastly the Braun air inlet. The presence of a valve confers an advantage when rapid infusion of fluid is attempted. The valve in the Codan air inlet performed best out of the inlets tested.

Air↗
PubMed1994

Vaporization of isoflurane by liquid infusion.

We investigated the vaporization of liquid isoflurane when infused directly into a circuit. Pooling of isoflurane occurred within the circuit tubing at infusion rates used during clinical practice when constant gas flows were used. Despite pooling, the concentration of isoflurane was linearly related to infusion rate. Cyclical gas flow, such as that seen in a circle system, increased vaporization so that pooling occurred only at the higher infusion rates used during the first five minutes of totally closed circuit anaesthesia. There were no major differences in pooling or the maximum concentration of isoflurane reached between 26 gauge needle and droplet administration of isoflurane: however the maximum concentration was reached more quickly by droplet administration. We conclude that direct infusion of liquid isoflurane into an anaesthetic circuit will result in complete vaporization during maintenance anaesthesia.

Anesthesia, Closed-Circuit↗
PubMed1990

Structure refinement of fructose-1,6-bisphosphatase and its fructose 2,6-bisphosphate complex at 2.8 A resolution.

The structures of the native fructose-1,6-bisphosphatase (Fru-1,6-Pase), from pig kidney cortex, and its fructose 2,6-bisphosphate (Fru-2,6-P2) complexes have been refined to 2.8 A resolution to R-factors of 0.194 and 0.188, respectively. The root-mean-square deviations from the standard geometry are 0.021 A and 0.016 A for the bond length, and 4.4 degrees and 3.8 degrees for the bond angle. Four sites for Fru-2,6-P2 binding per tetramer have been identified by difference Fourier techniques. The Fru-2,6-P2 site has the shape of an oval cave about 10 A deep, and with other dimensions about 18 A by 12 A. The two Fru-2,6-P2 binding caves of the dimer in the crystallographically asymmetric unit sit next to one another and open in opposite directions. These two binding sites mutually exchange their Arg243 side-chains, indicating the potential for communication between the two sites. The beta, D-fructose 2,6-bisphosphate has been built into the density and refined well. The oxygen atoms of the 6-phosphate group of Fru-2,6-P2 interact with Arg243 from the adjacent monomer and the residues of Lys274, Asn212, Tyr264, Tyr215 and Tyr244 in the same monomer. The sugar ring primarily contacts with the backbone atoms from Gly246 to Met248, as well as the side-chain atoms, Asp121, Glu280 and Lys274. The 2-phosphate group interacts with the side-chain atoms of Ser124 and Lys274. A negatively charged pocket near the 2-phosphate group includes Asp118, Asp121 and Glu280, as well as Glu97 and Glu98. The 2-phosphate group showed a disordered binding perhaps because of the disturbance from the negatively charged pocket. In addition, Asn125 and Lys269 are located within a 5 A radius of Fru-2,6-P2. We argue that Fru-2,6-P2 binds to the active site of the enzyme on the basis of the following observations: (1) the structure similarity between Fru-2,6-P2 and the substrate; (2) sequence conservation of the residues directly interacting with Fru-2,6-P2 or located at the negatively charged pocket; (3) a divalent metal site next to the 2-phosphate group of Fru-2,6-P2; and (4) identification of some active site residues in our structure, e.g. tyrosine and Lys274, consistent with the results of the ultraviolet spectra and the chemical modification. The structures are described in detail including interactions of interchain surfaces, and the chemically modifiable residues are discussed on the basis of the refined structures.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1990

Arterial oxygen saturation during induction of anaesthesia.

Three groups of 10 ASA 1 patients were studied to determine the incidence of hypoxaemia (oxygen saturation less than or equal to 90%) using pulse oximetry during induction of 'mask' anaesthesia, and whether simple oxygenation techniques could prevent its occurrence. We also surveyed all anaesthetists in three major hospitals to ascertain their techniques for this method of anaesthesia. Anaesthesia was induced in all patients with thiopentone and maintained with nitrous oxide and isoflurane. The first group received 33% oxygen in nitrous oxide as carrier gases, a second group a few normal breaths of 100% oxygen during thiopentone administration followed by 33% oxygen in nitrous oxide, while a third group received 100% oxygen after loss of eyelash reflex until spontaneous breathing was established. No patient received positive pressure ventilation before spontaneous breathing was established. Six of the 10 patients in the first group became hypoxaemic compared to none in the second group, and three patients became hypoxaemic in the third group. Thirty-seven percent of anaesthetists who responded to the survey either did not apply positive pressure ventilation before establishment of spontaneous breathing, or only did so if apnoea was prolonged. Only one anaesthetist fully pre-oxygenated patients lungs. We conclude that to avoid the likely occurrence of hypoxaemia during induction of mask anaesthesia, a minimum of a few breaths pre-oxygenation is necessary.

Adolescent↗
PubMed1989

Molecular structure of fructose-1,6-bisphosphatase at 2.8-A resolution.

Fructose-1,6-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) from the cortex of pig kidney and its complexes with either fructose 2,6-bisphosphate (Fru-2,6-P2) or adenosine monophosphate (AMP) have been crystallized in the space group P3(2)21. The three-dimensional structure of the native enzyme has been solved at 3.0-A resolution by the multiple isomorphous replacement method and refined at 2.8-A resolution to a crystallographic R factor of 0.194. A total of 316 of 335 residues, omitting disordered regions 1-5 and 54-67, have been built into the monomer, which has average dimensions of about 30 A by 50 A by 35 A. Four monomeric units aggregate into a molecular tetramer with D2 symmetry, which approximates a disk about 35 A thick. Each monomer consists of about 33% alpha-helix, 23% beta-strand, and 6% beta-turn. Four sites for Fru-2,6-P2 and two major sites for AMP binding per tetramer have been identified by difference Fourier techniques. The binding site for Fru-2,6-P2 is shared by two neighboring monomers and consists of side-chain atoms of Asn-212, Tyr-244, Tyr-264, and Lys-274; backbone atoms of Gly-246 through Met-248; and only Arg-243 from the adjacent subunit. In addition, Asn-125, Tyr-215, and Lys-269 are located within a distance of about 5 A of Fru-2,6-P2. A negatively charged pocket near this binding site includes Asp-118, Asp-121, Glu-280, Glu-97, and Glu-98. The AMP binding site is located near Val-17, Gln-20, Gly-21, Ala-24 through Met-30, Lys-112, Tyr-113, Arg-140, and Met-177.

Animals↗