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Biomedical subjects

R M Beihn

Publications and source records attributed to R M Beihn.

18 recordsLinked to original sources
PubMed1991

Dual-isotope imaging of neutron-activated erbium-171 and samarium-153 and the in vivo evaluation of a dual-labeled bilayer tablet by gamma scintigraphy.

The feasibility of dual-label scintigraphic studies which use the neutron-activated isotopes erbium-171 and samarium-153 is described. Experimental details are provided to correct and minimize the compton scatter contribution of 171Er into the lower-energy 153Sm window. The results from this study demonstrate that this dual-label procedure is sensitive enough to monitor simultaneously the behavior of two discrete regions of the same unit dose in the gastrointestinal tract of man.

Digestive System↗
PubMed1990

The effect of food on gastrointestinal (GI) transit of sustained-release ibuprofen tablets as evaluated by gamma scintigraphy.

The GI transit of radiolabeled sustained-release ibuprofen 800-mg tablets in eight healthy, fed volunteers was monitored using external gamma scintigraphy. Ibuprofen serum concentrations were determined from blood samples drawn over 36 hr following dosing. Sustained-release ibuprofen tablets containing 0.18% of 170Er2O3 (greater than 96% 170Er) in the bulk formulation were manufactured under pilot-scale conditions and were radiolabeled utilizing a neutron activation procedure which converted stable 170Er to radioactive 171Er (t1/2 = 7.5 hr). At the time of dosing, each tablet contained 50 mu Ci of 171Er. Dosage form position were reported at various time intervals. In five subjects the sustained-release tablet remained in the stomach and eroded slowly over 7-12 hr, resulting in gradual increases in small bowel radioactivity. In the remaining three subjects, the intact tablet was ejected from the stomach and a gastric residence time of approximately 4 hr was measured. This is in marked contrast to a previous study conducted in fasted volunteers in which gastric retention time ranged from 10 to 60 min. Differences in GI transit between fed and fasted volunteers had little effect on ibuprofen bioavailability. AUC and Tmax were unaltered and Cmax was increased by 24%, which is in agreement with results from a previous, crossover-design food effect study.

Adult↗
PubMed1989

Purposeful alteration of [99mTc]-pertechnetate biodistribution.

A series of imaging studies were conducted in rats to assess the effect of stannous containing chemical species on the normal biodistribution of [99mTc]pertechnetate. The goal of the study was to determine if tissue activity could be altered by use of selected chemical agents and if such alteration could be used to clear non-target activity for enhanced image interpretation and/or to visualize two or more organ systems following a single injection of radioactivity. Two distinct patterns of tissue activity alteration could be induced. Tissue distribution studies in rats demonstrated statistically significant differences between tissue radioactivity in groups selectively studied for the type and magnitude of the induced alteration.

Animals↗
PubMed1987

Correlation of ibuprofen bioavailability with gastrointestinal transit by scintigraphic monitoring of 171Er-labeled sustained-release tablets.

External gamma scintigraphy was used to monitor the gastrointestinal (GI) transit of radiolabeled sustained-release tablets containing 800 mg ibuprofen in eight fasted healthy volunteers. Ibuprofen serum concentrations were determined from blood samples drawn sequentially over a 24-hr period. Serum concentrations and related parameters were correlated to the position of the dosage form in the GI tract from the scintiphotos. The sustained-release tablets were radiolabeled intact utilizing a neutron activation procedure, by incorporating 0.18% of 170Er2O3 (enriched to greater than 96% 170Er) into the bulk formulation. After manufacture of the final dosage forms, the tablets were irradiated in a neutron flux (4.4 x 10(13) n/cm2.sec) for 2 min, converting the stable 170Er to radioactive 171Er (t1/2 = 7.5 hr). Each tablet contained 50 microCi of 171Er at the time of administration. The scintigraphy studies suggested that the greatest proportion of ibuprofen was absorbed from this dosage form while the tablet was in the large bowel. The dosage forms eroded slowly in the small bowel and appeared to lose their integrity in the large bowel. In vitro studies showed only minimal effects of the neutron irradiation procedure on the dosage form performance.

Biological Availability↗
PubMed1985

Disposition of radiolabelled suppositories in humans.

The disposition of Witepsol H 15 suppositories radiolabelled with [99mTc] technetium hydroxymethyldiphosphonate was studied after rectal administration in volunteers. The migration of the radiolabel was monitored continuously by external scintigraphy. The resulting scintiphotos were superimposed on lower GI radiographs to determine the extent of spreading of the dosage form in the rectum. The dosage form migrated approximately 5-7 cm into the rectum in nearly all of the studies and was, in general, confined to the lower and middle regions of the rectum. Since the venous supply to the lower rectum leads primarily to the inferior vena cava, the data presented here indicate that the metabolism of drugs sensitive to the 'first-pass' effect may be partially avoided by their rectal administration.

Adult↗
PubMed1981

Noninvasive dissolution measurement using perturbed angular correlation.

A novel noninvasive technique was developed to measure dissolution of the water-soluble component of a solid dosage form using indium 111 and perturbed angular correlation. The method involves time-delayed coincidence counting of two cascading gamma-rays that exhibit angular correlation. This angular correlation can be perturbed if the intermediate excited state of the nucleus is reoriented due to an interaction with its environment. When such an interaction occurs, as in a phase change (solid to liquid), the perturbation changes can be shown by anisotropy. A highly perturbed condition in the solid state results in low values (0.02-0.04), while increasing values of anisotropy indicate dissolution. Anisotropy values reach 0.14-0.15 when the total unperturbed physical state (liquid) exists. The worth of this technique was demonstrated by both in vitro and in vivo determinations of dissolution rates.

Gamma Rays↗
PubMed1980

Rate and pattern of gastric emptying in humans using 99mTc-labeled triethylenetetraamine-polystyrene resin.

The preparation and application of a new radiopharmaceutical used in the investigation of the rate and pattern of gastric emptying by external scintigraphy are described. Triethylenetetraamine was bound covalently to cross-linked chloromethylated polystyrene. The triethylenetetraamine-polystyrene resin tenaciously and rapidly bound technetium 99m. The gastric emptying rate was evaluated in normal adult volunteers and patients by serially recording the gastric radioactivity after ingestion of a test meal mixed with 99mTc-labeled triethylenetetraamine-polystyrene resin. The data indicated that 99mTc-labeled triethylenetetraamine-polystyrene resin was an ideal agent for assessing the rate and pattern of gastric emptying in humans. The gastric emptying half-time (t 1/2 GE) in normal subjects ranged from 25 to 75 min.

Ethylenediamines↗
PubMed1978

[Localization of Hodgkin's disease and non-Hodgkin lymphoma by means of 67 gallium subtraction scintigraphy].

67Ga-subtraction scan was found to be useful and a promising new method for the pre-treatment evaluation of the patient with Hodgkin's disease or non-Hodgkin's lymphoma. The scan appeared to be most accurate in the neck, chest, and axillary regions. It appears to offer a means of increasing the accuracy of evaluating the abdomen, the paraaortic and pelvic regions. It may be a useful method for follow-up to detect recurrences. It was an easily performed, safe, non-invasive test, well tolerated and accepted by patients.

Adult↗
PubMed1978

67Ga-subtraction scanning in Hodgkin's disease and lymphomas.

Recently a new method was described, the 67Ga subtraction scanning method. 67Ga accumulates in neoplastic and inflammatory tissue. The subtraction method was applied for evaluating 38 patients with Hodgkin's disease and non-Hodgkin's lymphoma. The preliminary experiences are described. It was found that the diagnostic accuracy is comparable to that of 67Ga scanning. The subtraction method offers potential improvement of the accuracy for equivocal scans, but further technological refinement is needed before the method can be widely applicable.

Diagnostic Errors↗
PubMed1977

Localisation of Hodgkin's disease and lymphomas by 67-gallium substraction scanning.

67Ga-subtraction scan was found to be useful and a promising new method for the pre-treatment evaluation of the patient with Hodgkin's disease or non-Hodgkin's lymphoma. The scan appeared to be most accurate in the neck, chest, and axillary regions. It appears to offer a means of increasing the accuracy of evaluating the abdomen, the para-aortic and pelvic regions. It may be a useful method for the follow-up to detect recurrences. It was an easily performed, safe, non-invasive test, well tolerated and accepted by patients.

Abdominal Neoplasms↗
PubMed1976

Detection of upper abdominal abscesses by radionuclide imaging.

An improved means of detecting upper abdominal abscesses using the dual radionuclide subtraction technique was applied to 51 patients. 67Gallium citrate was used in the localization of the lesion and 99Tc-labeled human albumin microspheres and 99Tc sulfur colloid were used for subtracting out the interfering background from normal organ concentrations. The procedure provided the parameter capabilities for localization of the abscesses as well as information on their shape and size. Compared to nonsubtraction Ga procedures, 53% more abscesses were diagnosed using the subtraction technique.

Abdomen↗
PubMed1975

The use of the 99mTc-pertechnetate neck/thigh ratio as a test of thyroid function.

A total of 100 patients were studied by standard thyroid function tests and the 99mTc-pertechnetate neck/thigh ratio was determined. This ratio or "trapping index" correlated closely with 131I uptake. The 99mTc test should be followed by scanning at 20 minutes to distinguish diffuse from localized thyroid disease. TSH stimulation and suppression studies can be done. It is recommended that this ratio be used in place of the standard 24-hour RAIU study, as it gives the same information at a saving in time, money, and radiation exposure.

Humans↗