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Biomedical subjects

R B Shafer

Publications and source records attributed to R B Shafer.

At least 73 records · Page 4Linked to original sources
PubMed1978

Comparison of two radioimmunoassays and a microbiologic assay for bleomycin.

Recently two radioimmunoassays have been independently developed for determination of bleomycin levels. In this study these assays are compared with each other and with a standard microbiologic assay for bleomycin. Bleomycin levels were determined in serum and urine samples obtained at varying intervals following intramuscular bleomycin injection. There were systematic differences between the assays. One radioimmunoassay indicated bleomycin levels lower than the levels indicated by the microbiologic assay with serum samples. With urine samples, both radioimmunoassays indicated bleomycin levels greater than the microbiologic assay.

Antibody Specificity↗
PubMed1978

A review of carotid cavernous fistula including diagnosis and evaluation by nuclear medicine angiography.

The various causes and differential diagnosis of carotid cavernous fistula are discussed as well as the description of the use of radionuclide angiography in the diagnosis and evaluation of patients with carotid cavernous fistulas. Radionuclide angiography has proven extremely useful in the diagnosis and follow-up of patients with carotid cavernous fistulas. The procedure is of maximum benefit in situations where repeat studies are required at frequent intervals. Five cases are described in which the nuclear medicine technique was instrumental in primary diagnosis and follow-up.

Adult↗
PubMed1978

Implications of liver activity associated with 133Xe ventilation lung scans.

A series of 35 xenon-133 (133Xe) ventilation studies yielded nine cases demonstrating accumulation of activity in the liver. Maximum intrahepatic deposition of radioxenon occurred during the washout phase of the study. In addition to those clinical instances which make this phenomenon possible, i.e., obesity, alcoholic-induced liver steatosis and diabetes mellitus, we found that hyperlipidemia and coronary artery disease also favor xenon-133 localization into the hepatic parenchyma. It is concluded that the lipid avidity of 133Xe facilitates its liver accumulation hyperlipidemic patients and in patients with coronary artery disease, and that this action may be explored to further understand deranged metabolic pathways in the liver of these patients. Hepatic accumulation of 133Xe during ventilation studies must be considered when assessing regional ventilation/perfusion relationships.

Adult↗
PubMed1978

Fenestrated sagittal sinus mimicking posterior cerebral infarction.

Two patients who presented with abnormal neurological findings and focal abnormalities on static brain imaging, were felt to have infarction in the distribution of the posterior cerebral artery. However, the posterior flow study delineated the cause of the abnormality as being a fenestrated anomaly of the sagittal sinus. The incidence of occlusive disease of the posterior cerebral artery, its clinical and scintigraphic presentation and the potential pitfalls for misinterpretation are reviewed.

Brain↗
PubMed1977

Pancreatic scanning using retrograde injection of technetium-99m-labeled compounds.

With increased clinical availability of endoscopic retrograde pancreatography, a method for retrograde injection of radionuclides into the pancreas became available. A dog model was developed to evaluate resolution and toxicity of retrograde imaging prior to human use. Two groups of technetium-99m-labeled compounds were used. The first included ionic carriers--pertechnetate and pyrophosphate--and the second included particulate carriers--sulfur colloid and albumin microspheres. Parenchymal visualization, absorption patterns, and toxicity in dogs were studied. The results suggest that pyrophosphate, sulfur colloid, and albumin microspheres would all be feasible technetium carriers for use in humans.

Animals↗
PubMed1977

A radioimmunoassay for bleomycin.

A radioimmunoassay for bleomycin, suitable for monitoring serum and urine drug levels, has been developed. Antisera were obtained from rabbits immunized with a conjugate of bleomycin and human serum albumin.Bleomycin labeled with 57Co was used as the tracer. Antibody-bound and free bleomycin were separated by precipitation with polyethylene glycol. The assay could determine bleomycin levels down to 0.025 mug/ml. The assay was precise, with a coefficient of variation of 2.8% Other drugs likely to be administered in combination with bleomycin did not interfere with the radioimmunoassay.

Animals↗
PubMed1976

Evaluation of the posterior flow study in brain scintigraphy.

To evaluate the usefulness of the posterior cerebral flow study, a prospective study was instituted. Of 32 adult patients examined for presumed posterior disease, 17 were found to have a positive posterior flow study that yielded information not available from the anterior study. Indications for posterior flow studies include posterior parietal, occipital, and posterior fossa tumors, posteriorly located arteriovenous malformations, Paget's disease involving occipital bone, posterior cerebral infarcts, and sagittal sinus occlusions. Our experience indicates that the posterior flow study is a valuable adjunct in those patients carefully screened for suspected posterior cerebral disease.

Adult↗
PubMed1976

Quality assurance for 99mTc-Sn-pyrophosphate.

Because skeletal images obtained with a commercial lyophilized preparation of 99mTc-Sn-pyrophosphate were occasionally degraded by liver and spleen uptake, a method for preparing 99mTc-Sn-pyrophosphate and a system for in-house quality assurance were developed. Control of the age of the stannous chloride solution and the final pH of the 99mTc-Sn-pyrophosphate eliminated the undesirable uptake. The quality and body distribution of the in-house preparation were compared to those of the radiopharmaceutical from a commercial kit.

Animals↗
PubMed1975

Acute changes in thyroid function in patients treated with radioactive iodine.

Serum triiodothyronine (T3) and thyroxine (T4) were measured in thirteen unselected hyperthyroid patients before and at frequent intervals after iodine-131 treatment. There was an abrupt rise in T3 from a pretreatment mean of 250 ng/100 ml to a maximum of 365 ng/100 ml at 24 hours. Total T4 rose from a mean of 18.7 mug/100 ml to a maximum of 22.3 mug/100 ml at 24-48 hours. These findings may explain why an occasional patient develops acute thyroid crisis after radioiodine treatment.

Adult↗
PubMed1975

Calcium and folic acid absorption in patients taking anticonvulsant drugs.

Calcium and folic acid absorption were studied in 28 adult male epileptics on chronic anticonvulsant therapy. In 16 patients on diphenylhydantoin alone, calcium absorption was abnormal in 9. In 12 patients on both diphenylhydantoin and phenobarbital, calcium absorption was abnormal in 3 patients. Folic acid (3H-PGA) absorption was normal in all but one patient, while serum folate (less than 6.4 ng/ml) was reduced in all patients. Hypocalcemia (less than 8.5 mg/100 ml) occurred in only 2 patients, while serum alkaline phosphatase was elevated in 7 patients. These findings support the proposal that rickets and osteomalacia reported in patients on chronic anticonvulsant therapy results from reduced calcium absorption. The effect of these drugs appears to be the acceleration of the metabolism of vitamin D and an increase in the excretion of polar metabolites. This may result in reduced levels of 25-hydroxycholecalciferol and 1,25-dihydroxycholecalciferol which are necessary for normal absorption of calcium. Since calcium absorption may be impaired secondary to a relative vitamin D deficiency, a supplemental increase in vitamin D intake by patients on anticonvulsant drugs is recommended.

Adult↗
PubMed1975

Changes in liver scan following splenectomy.

Changes in liver shape, position, and uptake of colloid have been noted by us in liver scans in patients following splenectomy. These changes have resulted in confusion in interpretation. Four cases are described to illustrate some of the possible misinterpretations. These include migration of the left lobe of the liver into the left upper quadrant mimicking residual or accessory spleen, mass lesion in the region of the porta hepatis, or recurrent foci of disease.

Adenocarcinoma↗