Dietary habits of first-year medical students assessed during clinical nutrition course.

To enhance the Introduction to Clinical Nutrition course at the University of Alabama at Birmingham, medical students taking the course from 1989 to 1992 (n = 616) were required to analyze by computer the nutrient composition of their own diets for a 24-h period. In 1991 and 1992, they were required to repeat the analysis at the completion of the course. Overall, fat comprised 30% of energy intake, and along with saturated fat and the cholesterol-saturated fat index, it declined virtually each year compared with the previous year. Significant changes were noted by the end of the course in 1991 and 1992 compared with the beginning, when fat comprised 26% of energy, and more students adhered to recommendations for dietary fat, saturated fat, and fiber. Vitamin C intakes exceeded the recommended dietary allowance by more than twofold and increased further by the end of the course in 1991 and 1992, probably indicating an increase in fruit and vegetable intake. Each year, most students rated the dietary assessment as moderately or very useful. These data suggest that dietary self-assessment is a useful tool for teaching clinical nutrition in medical schools and that, even before instruction in clinical nutrition, medical students are favorably altering their dietary patterns to a greater extent than the general population.

Tc-99m antifibrin Fab' fragments for imaging venous thrombi: evaluation in a canine model.

An antifibrin antibody (T2G1s) Fab' fragment labeled with technetium-99m was tested for its ability to produce images of fresh thrombi in dogs. In gamma camera images, all thrombi were evident by 2-4 hours after injection. Mean thrombus-to-blood and thrombus-to-muscle ratios averaged 4.0 and 69 at four hours after injection and increased to 24 and 270, respectively, by 24 hours after injection. When compared with I-125 fibrinogen injected into the same dogs, Tc-99m-antifibrin Fab' had lower absolute uptake in thrombus but higher thrombus-to-blood ratios due to a faster rate of disappearance from the blood. The primary route of excretion was through the kidneys. Tc-99m-antifibrin Fab' was highly stable in vivo, with an average of 82% of the circulating radioactivity able to bind to fibrin at 4 hours after injection. When compared with an In-111-labeled Fab fragment of antifibrin antibody 59D8, thrombus-to-blood and thrombus-to-muscle ratios were slightly higher for the Tc-99m-labeled antibody, and the blood disappearance rate was slightly faster. The absolute uptake in thrombus, however, was not significantly different, and the thrombus was visualized at about the same time after injection. These studies suggest that Tc-99m T2G1s Fab' is a potential agent for detecting thrombi in a clinical setting.

(3,6-Dimethyl-3,6-diazaoctan-1,8-dithiolato-S1,N3,N6,S8)oxotechnetium(V) pertechnetate.

[TcO(C8H18N2S2)]TcO4, Mr = 484.2, monoclinic, P2(1)/c, a = 7.447 (2), b = 16.952 (8), c = 12.236 (3) A, beta = 99.63 (2) degrees, V = 1523 (1) A3, Z = 4, D chi = 2.112, Dm = 2.09 (1) Mg m-3, lambda(Mo K alpha) = 0.71069 A, mu = 2.06 mm-1, F(000) = 952, T = 295 (1) K, final R = 0.071 for 2496 significant reflections and 173 parameters. The Tc atom is bound to the oxo group and the N and S atoms of the complex ligand in a rough square pyramid. The Tc atom lies 0.770 (3) A out of the S,N,N',S' plane. This plane is significantly distorted such that N and N' lie nearly 0.25 A out of the plane on opposite sides. The Tc-S bonds [2.238 (3), 2.266 (3) A] are short but other bond lengths and angles are normal.

Brain imaging agents: synthesis and characterization of (N-piperidinylethyl) hexamethyl diaminodithiolate oxo technetium(V) complexes.

Two 99mTc complexes of (N-piperidinylethyl) hexamethyl diaminodithiol (NEP-DADT) have shown high brain uptake in rodents and lower primates. One of these 99mTc complexes has given positive images of the brain in man which are qualitatively related to regional brain blood flow (rCBF). In order to determine the structure of these 99mTc products, the corresponding 99Tc(NEP-DADT) complexes were prepared and characterized by HPLC, TLC, fast-atom-bombardment mass spectrometry (FAB MS) and other analytical techniques. These results indicate that the two 99Tc (NEP-DADT) complexes are syn and anti isomers (i.e. one isomer has the N-piperdinylethyl side chain located syn to the technetium oxo core while the other has this side chain located anti to the technetium oxo core).

Design, preparation, and biodistribution of a technetium-99m triaminedithiol complex to assess regional cerebral blood flow.

A new ligand (N-piperidinylethyl-DADT, 5) has been prepared which forms two complexes with 99mTc when stannous chloride is used as a reducing agent for [99mTc] pertechnetate. Biodistribution studies of one of the complexes in mice showed that 2.2% of the injected dose of the tracer was in the brain at 5 min postintravenous injection with 0.53% of the dose remaining in the brain at 30 min postinjection. Brain-to-blood ratios at these times were 5.3 and 3.0, respectively. Biodistribution studies of the other complex showed similar behavior with a slightly lower initial uptake by and faster clearance from the brain. Imaging studies of the more promising of the two complexes were conducted in a monkey and a baboon. In both cases, rapid uptake of the tracer in the brain was observed and clear brain images were obtained. Time-activity curves showed peak uptake in the brain at approximately 5 to 7 min postintravenous injection followed by a plateau of about 11 min. The half-lives for clearance of the tracer from the brains of the monkey and baboon were found to be 63 and 58 min, respectively. These results suggest that this tracer may be useful for brain imaging in humans.