Search PubMed⌕ Search

Biomedical subjects

R N Bryan

Publications and source records attributed to R N Bryan.

At least 127 records · Page 7Linked to original sources
PubMed1975

Effects of contrast agents on the blood-brain barrier. An electron microscopic study.

To determine if contrast agents after the blood-brain barrier by opening tight junctions between endothelial cells and by increasing pinocytosis, the distribution of horseradish peroxidase (HRP) was evaluated after intracarotid injections of contrast media. HRP did not cross the endothelium of cerebral blood vessels. Tight junctions remained closed. There was increased endothelial cell pinocytosis and swelling of astrocyte end-feet.

Animals↗
PubMed1966

Retrograde amnesia: effects of handling and microwave radiation.

Rats that were irradiated with microwaves immediately after the training trial in a one-trial shock-avoidance learning task retained the conditioned avoidance response 24 hours later. However, rats that were handled a few minutes each day for 3 days before the experiment did not retain the response, although they were capable of learning in a later test.

Amnesia↗
PubMedDate not supplied

Radiographic staging of juvenile angiofibroma.

A staging system for juvenile angiofibroma based on computerized tomographic findings is suggested. The need for such an endeavor has come about because of a lack of standardization of tumor data in both individual series and interinstitutional reports. The various stages reflect the number of anatomic sites occupied by a lesion rather than the actual tumor size. The "simpler" tumors are confined to the medial part of the skull base and are entirely extracranial. As a tumor extends laterally and/or intracranially, the staging designation, and therefore the treatment plan, changes accordingly. Presumably, with the application of consistent diagnostic tools and standardized stage designations, the analysis of both morbidity and treatment data will become more meaningful.

Histiocytoma, Benign Fibrous↗
PubMedDate not supplied

Quantitation of proton NMR spectra of the human brain using tissue water as an internal concentration reference.

The use of cerebral water as an internal intensity standard for the quantitation of spatially localized proton spectra of the human brain is investigated. The method is validated on standard samples of N-acetyl aspartate (NAA) and lactate, and possible sources of error are discussed. Using the STEAM pulse sequence, concentrations of choline, creatine and NAA in frontal lobe white matter are found to be 1.9 +/- 0.5, 10.6 +/- 1.3 and 16.6 +/- 2.3 mumol/g wet wt, respectively, in 10 normal volunteers. In the thalamus, the concentrations are 2.0 +/- 0.4, 11.6 +/- 2.0 and 17.2 +/- 1.3 mumol/g wet wt, respectively. Choline and creatine concentrations are in good agreement with conventional biochemical values: NAA concentrations are found to be three-fold higher, suggesting overlap of the NAA signal with other compounds. Quantitation relative to tissue water is a convenient and rapid means of quantitating proton spectra of the human brain.

Adult↗
PubMedDate not supplied

Computed tomography in infantile spasms: effects of hormonal therapy.

During a prospective double-blind, crossover study of ACTH versus prednisone therapy, serial computed tomography (CT) scans were performed on 16 children with infantile spasms. Pre-treatment scans revealed four findings: normal (6 patients), generalized atrophy (bilaterally enlarged ventricles and/or subarachnoid space) (2 patients), predominantly focal atrophy (3 patients), and congenital anomalies (5 patients). Within 2 weeks of initiating relatively low therapeutic dosages of ACTH or prednisone, a significant number of the infants (63%) had CT findings consistent with decreased cortical volume; in many cases (44%), these findings had not reversed 4 to 6 weeks after discontinuing therapy. Duration of therapy did not correlate significantly with the persistence of CT changes.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Destructive encephalopathy in incontinentia pigmenti: a primary disorder?

A 3-day-old infant with incontinentia pigmenti presented with acute encephalopathy associated with neuroradiographic findings of hemorrhagic necrosis and brain edema. No specific infectious, inflammatory, vascular, or metabolic abnormality was identified. We speculate that there is a variably expressed mutant protein in incontinentia pigmenti that could cause either developmental brain malformations or a destructive process.

Brain Diseases↗