31P nuclear magnetic resonance studies of cell membranes labelled with phosphonium phosphatidylcholine.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
E Sim
Publications and source records attributed to E Sim.
The metabolism of the phosphonium analogue of choline in cultured cells. A useful nuclear-magnetic-resonance probe for membrane phosphatidylcholine.
1. Replacement of choline by the phosphonium analogue does not affect the growth rate of P815Y, NIL, 3T3, and SV40/3T3 cells in culture. 2. The fatty acid composition of the resulting phosphonium phosphatidylcholine is similar to that of phosphatidylcholine. 3. The rate of synthesis and degradation of phosphatidylcholine and of the phosphonium analogue are similar. 4. Phospholipid-exchange protein does not distinguish between phosphatidylcholine and the phosphonium analogue. 5. By contrast, incorporation of phosphonium choline into sphingomyelin occurs to only a minor extent. 6. It is concluded that, since the enzymes involved in the turnover of phosphatidylcholine do not discriminate between quaternary N and quaternary P in the polar head-group region, phosphonium choline should prove to be a useful probe for 31P nuclear-magnetic-resonance (n.m.r.) studies of natural membranes.
Cell Line↗
Physical studies on phosphonium phosphatidylcholine. A unique [31P]phosphorus nuclear-magnetic-resonance probe for model and biological membranes.
1. Distearoyl phosphatidylcholine and the phosphonium analogue, in which the nitrogen atom is replaced by phosphorus, show similar gel-liquid crystalline transition temperatures as detected by differential scanning calorimetry. 2. The temperature-dependence of the 31P n.m.r. (nuclear-magnetic-resonance) linewidths of the phosphate resonances of sonicated vesicles of distearoyl phosphatidylcholine and the phosphonium analogue are similar. Below the phase-transition temperature the linewidths decrease as the temperature is raised. Above the phase-transition temperature the phosphate resonances are relatively temperature-independent. The phosphonium 31P n.m.r. signal exhibits the same pattern of temperature-dependence. 3. The 31P n.m.r. phosphonium resonance is sensitive to the paramagnetic shift reagent, K3Fe(CN)6. Use of K3Fe(CN)6, together with Nd(NO3)3, enabled the determination of the trans-bilayer distribution of egg-yolk phosphatidylcholine and its phosphonium analogue in co-sonicated vesicles. Both are distributed comparably across the bilayer of the vesicles. 4. The phosphonium 31P n.m.r. signal is much sharper than the corresponding phosphate resonance in both sonicated and unsonicated dispersions of the phosphatidylcholine analogue. 5. The properties of the phosphonium analogue of phosphatidylcholine are discussed in terms of its suitability as a probe of membrane structure.
Calorimetry↗
Peroral tunable-dye laser lithotripsy of intrahepatic stones in oriental cholangitis.
This case report details the use of a pulsed tunable-dye laser lithotripter in the endoscopic management of recurrent intrahepatic stones in a patient with Oriental cholangitis. A 42-year-old Chinese man had a cholecystectomy and choledochoduodenostomy in 1980. Subsequently he had three episodes of recurrent cholangitis which responded to medical treatment. The patient presented in April 1989 with a fourth attack of cholangitis. Endoscopic retrograde cholangiopancreatography (ERCP) and ultrasound demonstrated a large mass of stones in the right intrahepatic ductal system. A flexible upper gastrointestinal endoscope was passed into the right hepatic duct via the choledochoduodenostomy. The stones were fragmented with a tunable-dye laser and the residual fragments were removed endoscopically.
Adult↗
[Unicameral cyst of the calcaneus: surgical indications, biomechanical calculations and results of follow-up studies].
Between April 1986 and August 1988, 7 patients (6 men, 1 woman) with unicameral calcaneal cysts were seen at the Trauma Hospital in Meidling. In one case both calcanei were affected. In all cases the findings were accidental, as a result of minor injuries. No familial preponderance was observed. The mean age of the patients was 26.6 years (19 to 33). In 3 patients, filling of the cyst was indicated due to risks from sport or occupational activities. Four cysts were therefore filled with fibrin-spongiosa (homologous bone chips). The mean follow-up interval was 19 months. No recurrent cyst formation was observed, and the patients had no complaints. Nor were there any complications. The importance of CT for preoperative diagnosis and postoperative verification of the result is indicated. On the basis of a strut framework model, it is proved mathematically that cyst formation is not of major importance for the "vertical load case"; on the other hand, bending moments occurring in "inclined load cases" (pronation, supination, extension, flexion), are substantially reduced if the cancellous bone in the cavity region is taken into account. As a logical consequence, surgery is indicated in individuals as risk due to occupational or sports activities; in cases which are not subject to stress peaks, however, therapy is unnecessary.
Adult↗
Immunotoxic side-effects of drug therapy.
Adverse reactions to drugs in which an immune mechanism is responsible for toxicity have been described as idiosyncratic. Understanding these toxic effects is important to enable the identification of patients at risk. The specific toxic side effects considered are heparin-induced thrombocytopenia, penicillin-induced haemolytic anaemia, hepatitis as a result of halothane and tienilic acid therapy, quinine- and quinidine-dependent thrombocytopenia, methyldopa-induced haemolytic anaemia and immune-complex disease following administration of hydralazine, procainamide and penicillamine. The molecular mechanisms of immunotoxicity are presented where such information is available although more than one effect may contribute to the observed pattern of toxicity. The initial events leading to antibody production in certain individuals in response to drug therapy are not understood and, in many of the examples described, antibody production occurs in some patients who do not subsequently experience clinical problems. Clinically serious adverse effects involving immune reactions are infrequent, and a range of genetic and environmental circumstances need to be present simultaneously in an individual before toxicity develops. The ability to metabolise a particular drug has been shown to be one major predisposing factor in toxicity; the immunocompetence of the patient is likely to be another. Both of these considerations are subject to genetic and environmental controls, including infection and disease.
Drug-Related Side Effects and Adverse Reactions↗