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Biomedical subjects

S Zoghbi

Publications and source records attributed to S Zoghbi.

23 records · Page 2Linked to original sources
PubMed1990

Receptor binding characterization of the benzodiazepine radioligand 125I-Ro16-0154: potential probe for SPECT brain imaging.

The binding of an iodinated benzodiazepine (BZ) radioligand has been characterized, particularly in regard to its potential use as a neuroreceptor brain imaging agent with SPECT (Single Photon Emission Computed Tomography). Ro16-0154 is an iodine-containing BZ antagonist and a close analog of Ro15-1788. In tissue homogenates prepared from human and monkey brain, the binding of 125I-labeled Ro16-0154 was saturable, of high affinity (Kd = 0.5 nM at 37 degrees C), and had high ratios of specific to non-specific binding (approximately 40:1). Physiological concentrations of NaCl (150 mM) enhanced specific binding approximately 15% compared to buffer without this salt. Kinetic studies of association and dissociation demonstrated a temperature dependent decrease in affinity with increasing temperature. Drug displacement studies confirmed that 125I-Ro16-0154 binds to the "central" type BZ receptor: binding is virtually identical to that of 3H-Ro15-1788 except that 125I-Ro16-0154 shows an almost 10 fold higher affinity at 37 degrees C. These in vitro results suggest that 123I-labeled Ro16-0154 shows promise as a selective, high affinity SPECT probe of the brain's BZ receptor.

Animals↗
PubMed1989

A quantitative study of relaxation rate enhancement produced by iron oxide particles in polyacrylamide gels and tissue.

The proton relaxation rate enhancements produced by two types of iron oxide particles, M4125 and AM125 (Advanced Magnetics, Cambridge, MA) designed as potential MR contrast agents, have been measured in polyacrylamide gels and in liver and spleen. The organ uptakes, time courses, and biodistributions of these materials have been measured using radiolabeling. The relaxation rate enhancements produced by these particles have been related to the concentration of iron per gram material at different magnetic field strengths. The relaxation rates increase linearly as a function of concentration at field strengths varying from 0.15 to 7 T. The relaxation effects of these particles in tissue are significantly different from the behavior in vitro. These results suggest that several different mechanisms contribute to relaxation effects in the presence of iron oxide particles and they depend strongly on the way the particles are sequestered. Diffusion effects for a specified TE may be enhanced using gradient or single-spin echoes rather than multiple echoes. AM125 is significantly more effective as a relaxation agent than paramagnetic metal ions only at relatively high fields, while M4125 is less effective per unit concentration.

Acrylic Resins↗
PubMed1988

Quantitation of MR relaxation effects of iron oxide particles in liver and spleen.

The relaxation effects and organ distribution of superparamagnetic iron oxide particles for magnetic resonance imaging were measured in rats. T1 and T2 were measured for excised organs, and tissue iron levels were quantified with radiolabeling. Approximately 70% of the injected dose is present in the liver and 10% in the spleen 1 hour after injection. At 20 MHz, the doses required to reduce liver and spleen T2 to half the normal value, as measured with a Carr-Purcell-Meiboom-Gill sequence, were, respectively, 420 and 830 mumol iron injected per kilogram of rat. The transverse relaxation rates increase linearly with injected dose and showed no evidence of saturation. These results suggest that this material is less effective than previously suggested.

Animals↗
PubMedDate not supplied

[Preoperative endoscopic sphincterotomy].

We present a prospective unrandomized series of 40 patients with symptomatic choledocholithiasis and symptomatic cholelithiasis. The patients were divided in two groups of 20 patients each one. The patients fallen in the first group had endoscopic sphincterotomy and elective cholecystectomy on a later date in the same hospital course as the recommended treatment. The second group underwent elective cholecystectomy and common bile duct exploration. There was no difference in the percentage of morbidity and mortality between the groups. In the first group the figures on morbidity and mortality were not different from that seen when each process was performed alone. Endoscopic Sphincterotomy plus elective cholecystectomy is a therapeutic alternative in choledocholithiasis when there is gallbladder with stones.

Adult↗