Biomedical subjects

J A Clanton

Publications and source records attributed to J A Clanton.

41 records · Page 3Linked to original sources

PubMed1983

Murine eosinophils labeled with indium-111 oxine: localization to delayed hypersensitivity reactions against a schistosomal antigen and to lymphokine in vivo.

We have evaluated a method for quantitation of eosinophil migration to stimuli in vivo. Upon transfusion into normal syngeneic mice, 111In-labeled eosinophils had an intravascular half-life of 9.5 hr and distributed predominantly into spleen, bone marrow, and liver. In either Schistosoma mansoni-infected mice or recipients of lymphoid cells from infected mice, intradermal (ear pinna) injection of the schistosomal egg antigenic preparation (SEA) elicited time-dependent accumulation of 111In-labeled eosinophils detectable by either gamma scintillation counting of tissue samples or by nuclear medicine external imaging. Intradermal administration of a lymphokine fraction (containing eosinophil stimulation promoter activity) similarly caused accumulation of 111In-labeled eosinophils. Both reactions depended on the concentration of stimulus (SEA or lymphokine). 111In-labeled neutrophils or macrophages or 125I-albumin did not preferentially accumulate at the reactions examined to the extent found with 111In-labeled eosinophils, indicating that localization of label depends on an active process and is due to eosinophils rather than a contaminating cell type. The method was used to estimate how long eosinotactic lymphokine remained at dermal sites: 60% of initial activity was present 12 hr after injection. The model is discussed with regard to the role of lymphokines in hypersensitivity reactions with eosinophil involvement, such as the granulomatous response to S. mansoni eggs.

Animals↗

PubMed1982

Localization of gelfoam emboli after partial splenic embolization utilizing 99mTc-labeled emboli.

Partial splenic embolization using 99mTc-labeled Gelfoam was employed to manage of four renal transplant patients with thrombocytopenia and leukopenia. In each patient the individual Gelfoam particles could be seen on the persistence scope of a gamma camera as they arrived in the spleen. This allowed the precise location of each Gelfoam particle to be defined immediately. Gamma camera imaging of the 99mTc Gelfoam particles in the spleen proved as accurate as selective splenic arteriography in determining the amount of spleen embolized. No ectopic 99mTc Gelfoam particles were found as judged by total body gamma camera imaging obtained immediately after the partial splenic embolization procedure was completed.

Adolescent↗

PubMedDate not supplied

Comparison of CT and MRI brain tumor imaging using a canine glioma model.

A canine gliosarcoma model was used to study the effectiveness of magnetic resonance imaging (MRI) with gadolinium contrast enhancement in defining the histologic margins of brain tumors. The effectiveness of this technique was compared to conventional computed tomography (CT) using iodinated contrast enhancement. Cultured canine gliosarcoma cells were injected into the left hemisphere of adult mongrel dogs. The dogs developed brain tumors and progressive clinical signs. Serial MRI with and without gadolinium diethylene triamine penta-acetic acid was compared to serial CT with and without sodium iothalamate obtained on the same days. After the final scans, animals were sacrificed; the brains were removed and processed for routine histopathologic study. All tumors were visualized with contrast-enhanced MRI which proved most sensitive. Gadolinium di-ethylene triamine penta-acetic acid caused bright enhancement of tumors in a distribution that consistently corresponded to areas of pathologically proved tumor infiltration. Gross and microscopic autopsy findings correlated better with MRI than with CT which tended to produce poorer resolution and underrepresent the size of viable tumor. Gadolinium-enhanced MRI is more accurate than unenhanced MRI, unenhanced CT, or enhanced CT in defining the histologic margins of tumors.

Animals↗

PubMedDate not supplied

Paramagnetic NMR contrast agents. Development and evaluation.

Paramagnetic ions could be theoretically used as NMR contrast agents because of their effect upon T1. However, the toxicity of these ions prevents their application. By the formation of appropriate chemical complexes with these ions, the toxicity of these agents can be substantially reduced while maintaining the paramagnetic effect. Two potential NMR contrast agents, one for oral use and one for intravenous administration, were developed and evaluated both in vitro and in vivo. The effect upon T1 in vitro of these paramagnetic compounds was determined using a JEOL FX-90Q NMR spectrometer. These agents were evaluated in vivo in dogs with a Technicare 0.3 tesla superconducting magnet system and in rabbits with the Aberdeen 0.04 tesla resistive NMR imager. Using calculated T1 NMR images, a nontoxic dose of gadolinium oxalate provided visualization of the gastrointestinal tract. Intravenous administration of chromium EDTA provided enhancement of the kidneys, ureters, and bladder, thereby potentially allowing for the evaluation of renal function with magnetic resonance imaging. Stable paramagnetic complexes can serve as effective, nontoxic, oral and intravenous NMR contrast agents.

Administration, Oral↗

PubMedDate not supplied

Dyke Award. Evaluation of contrast-enhanced MR imaging in a brain-abscess model.

An alpha-streptococcus brain abscess was produced in five dogs and studied with magnetic resonance (MR) imaging (0.5 T) and computed tomography (CT). Non-contrast- and contrast-enhanced CT scans were obtained using gadolinium diethylenetriamine-pentaacetic acid (Gd DTPA) for MR imaging and meglumine iothalamate for CT scanning. Each animal was evaluated in the early and later cerebritis stages of abscess evolution. On MR, the area of cerebritis enhanced after administration of Gd DTPA in a manner similar to that observed with contrast-enhanced CT. However, contrast enhancement was greater on the MR examination. Early lesions in two animals were detected only with contrast-enhanced MR imaging. This experience suggests that intravenously administered agents such as Gd DTPA should increase the diagnostic potential of MR imaging in neurologic diseases, especially those altering the blood-brain barrier.

Animals↗