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Biomedical subjects

G A Francis

Publications and source records attributed to G A Francis.

9 recordsLinked to original sources
PubMed1995

Recovery from neuromuscular blockade: residual curarisation following atracurium or vecuronium by bolus dosing or infusions.

We conducted a survey of the incidence of Postoperative Residual Curarisation (PORC) in two groups of patients following the use of atracurium or vecuronium. In the first group (B) the neuromuscular blocking drugs were administered by bolus dosing, and in the second group (I) by continuous fusion. On arrival in the recovery room, neuromuscular function was assessed both by compound evoked electromyogram (EMG) in a train of four pattern and also clinically, by the ability to sustain a headlift for > 5 seconds, and to cough. Results were obtained from 150 patients (100 in group B and 50 in group I). The incidence of PORC, as defined by a train of four ratio of < 0.7, on arrival in the recovery room was 12% in group B, and 24% in group I. Clinical criteria of adequate neuromuscular reversal revealed different results, with the majority of patients being unable to perform either clinical test on arrival in recovery. Those patients in whom a peripheral nerve stimulator was used intra-operatively did not have a reduced incidence of PORC. We have demonstrated that PORC is still a common occurrence even with intermediate duration of action neuromuscular blocking drugs.

Adolescent↗
PubMed1995

Defective removal of cellular cholesterol and phospholipids by apolipoprotein A-I in Tangier Disease.

Tangier disease is a rare genetic disorder characterized by extremely low plasma levels of HDL and apo A-I, deposition of cholesteryl esters in tissues, and a high prevalence of cardiovascular disease. We examined the possibility that HDL apolipoprotein-mediated removal of cellular lipids may be defective in Tangier disease. With fibroblasts from normal subjects, purified apo A-I cleared cells of cholesteryl esters, depleted cellular free cholesterol pools available for esterification, and stimulated efflux of radiolabeled cholesterol, phosphatidylcholine, and sphingomyelin. With fibroblasts from two unrelated Tangier patients, however, apo A-I had little or no effect on any of these lipid transport processes. Intact HDL also was unable to clear cholesteryl esters from Tangier cells even though it promoted radiolabeled cholesterol efflux to levels 50-70% normal. Passive desorption of radiolabeled cholesterol or phospholipids into medium containing albumin or trypsinized HDL was normal for Tangier cells. Binding studies showed that the interaction of apo A-I with high-affinity binding sites on Tangier fibroblasts was abnormal. These results indicate that apo A-I has an impaired ability to remove cholesterol and phospholipid from Tangier fibroblasts, possibly because of a defective interaction of apo A-I with cell-surface binding sites. Failure of apo A-I to acquire cellular lipids may account for the rapid catabolism of nascent HDL particles and the low plasma HDL levels in Tangier disease.

Apolipoprotein A-I↗
PubMed1991

Regulation of the uptake of high-density lipoprotein-originated cholesteryl ester by HepG2 cells: role of low-density lipoprotein and plasma lipid transfer protein.

Cholesteryl ester uptake by the human hepatoma cell line HepG2 was studied in vitro by using radiolabeled cholesteryl ester as a tracer. After the cells were incubated in a lipoprotein deficient condition, the rate of radio labeled cholesteryl ester uptake from low-density lipoprotein (LDL) was estimated to be some 25-times higher than that from high-density lipoprotein (HDL). LDL-cholesteryl ester uptake was suppressed by preincubation of the cells with LDL, but pretreatment of the cells with HDL did not show significant effect. HDL-cholesteryl ester uptake was only slightly suppressed by pretreatment of the cells with LDL, and there was no effect with HDL pretreatment. HDL-cholesteryl ester uptake was not affected either by the presence of LDL or human plasma lipid transfer protein alone in the medium under our experimental conditions. Lipid transfer protein enhanced the uptake of radiolabeled cholesteryl ester originating from HDL by the cells only in the presence of LDL. Thus, lipid transfer protein catalyzes a bypass to LDL for the uptake by HepG2 cells of cholesteryl ester molecules which originate in HDL, and this pathway is much more efficient than direct uptake of cholesteryl ester originating in HDL by these cells.

Binding, Competitive↗
PubMed1991

A serious complication of minitracheotomy.

A previously unreported complication of minitracheotomy is described. The minitracheotomy introducer was lost into the pleural cavity and a thoracotomy was required to remove it.

Adult↗
PubMed1980

Localization of photosynthetic membrane components in Rhodopseudomonas sphaeroides by a radioactive labeling procedure.

Reduction with [3H]KBH4 of Schiff's bases generated by reaction with pyridoxal 5'-phosphate (which cannot penetrate the intact cytoplasmic membrane) yields tritium-labeled derivatives of both proteins and lipids accessible on the periplasmic side of the cytoplasmic membrane. Application of this technique to phototrophically grown Rhodopseudomonas sphaeroides labeled both the cell envelope and chromatophore fractions. The technique was also applied to R. sphaeroides harvested at various times during an adaptation from heterotrophic to phototrophic growth conditions. The specific activity of the chromatophore fraction after 20 h of adaptation was 76% of that found at the beginning, indicating that the intracytoplasmic membranes and cytoplasmic membrane form a continuous membrane system, with the majority of the intracytoplasmic membranes accessible to the external medium throughout the adaptation. The identity of the proteins labeled by this technique was investigated in two fractions labeled after cell disruption: normal "inside-out" chromatophores and "right-side-out" membrane vesicles isolated by lysozyme--osmotic shock treatment of cells grown in high light intensity (15000 lx). The results after sodium dodecyl sulfate--polyacrylamide gel electrophoresis and fluorography indicated that the 28000-dalton subunit (and to a lesser extent the 21000-dalton subunit) of the reaction center complex and two polypeptides in the light-harvesting region of the gel were heavily labeled in the chromatophores and were thus accessible on the cytoplasmic side of the membrane. At least one of the latter two polypeptides was also labeled in the membrane vesicles and was thus also accessible on the periplasmic side of the membrane. None of the reaction center subunits was significantly labeled in a reaction center complex prepared from the membrane vesicle sample.

Bacterial Chromatophores↗