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Biomedical subjects

D G Potts

Publications and source records attributed to D G Potts.

17 recordsLinked to original sources
PubMed1992

Evaluation of the integrity of the blood-brain barrier after meningeal trauma.

RATIONALE AND OBJECTIVES: The authors used magnetic resonance imaging (MRI) techniques to examine the effect of meningeal trauma produced by cisterna magna puncture on the integrity of the blood-cerebrospinal fluid barrier (BCB) in a rat model. METHODS: Intravenous gadolinium-DTPA (Gd-DTPA), a relaxation rate modifier which normally does not cross the BCB, was used as a probe to follow leakage of fluid across the BCB. After Gd-DTPA injection, cerebrospinal fluid (CSF) serial samples were obtained through the needle used to create the experimental trauma. These samples were subsequently examined in vitro by MRI to obtain their T1 relaxation rates and assayed by mass spectrometry for gadolinium and elemental iron concentrations. RESULTS: The iron levels reflected the severity of puncture-related subarachnoid hemorrhage. Rats with ongoing meningeal damage showed significantly higher CSF levels of gadolinium and significantly higher CSF T1 relaxation rates than controls at all samples times over 1 hour after the puncture. Blood in the CSF could not explain these changes because the CSF iron levels did not significantly differ from control levels. CONCLUSIONS: Intravenously administered Gd-DTPA can gain access to the subarachnoid space through minor defects in the BCB and cause significant increases in CSF T1 relaxation rates.

Animals↗
PubMed1992

High-resolution magnetic resonance imaging of experimental spinal cord injury in the rat.

The ability of magnetic resonance imaging (MRI) to display the anatomic changes after spinal cord injury in the rat were examined in postmortem specimens. With the clip compression technique, acute spinal cord injuries of three grades of severity were produced in adult male rats. One hour after injury, during which time physiological parameters were measured and maintained within the normal range, the rats were killed by transcardiac perfusion of formalin. The vertebral column containing the cervical and upper thoracic segments was excised and, after further formalin fixation, 20 contiguous MRI scans centered on the injury site were obtained using a spin-echo imaging sequence. The volume of signal acquisition for each image was 15 x 15 x 1.0 mm thick. The spinal cords were then removed from the vertebral column, sectioned, and stained for histological examination. Ten-micrometer serial sections of each cord were examined microscopically. MRI scans and microscopic sections at comparable levels were examined to determine the quality of anatomical detail and spatial resolution of the MRI scans. MRI scans with resolution of about 75 microns per pixel edge were obtained. At the site of injury, there was disruption of the normally well demarcated gray-white interface and variable areas of low signal intensity. Because of the resolution achieved, it was possible to determine that these low signal intensity areas were post-traumatic hemorrhages. Indeed, hemorrhages with dimensions of the order of 100 microns were detected on the MRI scans. Furthermore, by examining the serial sections of the cord, the extent of the injury along the cord could be determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Passage of Amipaque (metrizamide) through the arachnoid granulations.

125I labelled Amipaque (metrizamide) was introduced by cisternal puncture into six rabbits and perfused at various pressures. The torcular was exposed, frozen rapidly, and excised intact. Sections of arachnoid proliferations were made from the frozen specimen and either freeze dried or sandwiched directly for autoradiography. Some specimens were freeze dried en bloc prior to sectioning and sandwiching. All sections were exposed for 2-3 weeks at -80 degrees C prior to development of the autoradiographs. On microscopic examinations of the autoradiographs most of the activity was in the tubules or between cells suggesting intercellular passage. Some label was also present within the brain. The significance of this is discussed.

Absorption↗
PubMed1978

Microradiographic study of cerebral and ocular aneurysms in hypertensive rabbits.

Cerebral and ocular microaneurysms were produced in rabbits made hypertensive by surgically induced silk-turpentine perinephritis combined with contralateral nephrectomy 7 days later. The aneurysms distributed throughout the brain and iris were studied by microradiography; a few representative aneurysms selected from the microradiographs were studied histologically. The microradiographic findings and histological sections correlated well. Intracranial microaneurysms were multiple and frequently located in the basal ganglia and near the cortex. Arterial changes in the iris paralleled intracranial arterial changes in degree and type except for the addition of hemorrhage around some microaneurysms. The results of this study show the potential of microradiography and histological sections guided by microradiography for studying the natural history of hypertensive arterial lesions and support the contention that hypertension, microaneurysms and intracerebral hemorrhages are related.

Aneurysm↗
PubMed1978

A new device for myelography.

A new device based on the principle of the concentric system has been constructed for myelography and certain other procedures. It consists of biplane tube-image amplifier systems with 105-mm cameras in both planes. The system gives superior visualization of water-soluble media, particularly when tomography is used. The radiation dose to the patient is low.

Humans↗
PubMed1977

Possible causes of complications of myelography with water-soluble contrast medium.

The mechanisms of CSF formation and absorption have been reviewed. The conditions that alter the rate of CSF formation and absorption may change the concentration of contrast in the cranial cisterns and the rate of passage through the cisterns. The significance of these alterations in relation to the complications of myelography with water-soluble contrast media is discussed.

Contrast Media↗
PubMed1976

Human spinal arachnoid villi and granulations.

Human spinal arachnoid villi and granulations were studied after distension by a subarachnoid perfusion of Berlin blue and trypan blue. These proliferations were distributed on almost every nerve root in the thoracic and lumbar region. Human spinal arachnoid villi and granulations were divided into those located entirely internal to the dura, those that extended into the dura, and those that penetrated the dura completely. Venous sinuses were closely related to most arachnoid proliferations.

Arachnoid↗
PubMedDate not supplied

Evidence for transventricular absorption in the hydrocephalic dog.

Hydrocephalus was induced in 10 mongrel dogs by injection of a silastic mixture into the basal cisterns. The posterior part of the left lateral ventricle was isolated from the remainder of the ventricular system by introducing Pantopaque into both lateral ventricles and the third ventricle with the animals in prone positions. Labeled albumin injected into the posterior part of the left lateral ventricle was shown to enter the blood stream before it was shown in the fourth ventricle or vallecula. This provides qualitative evidence of transventricular absorption.

Absorption↗
PubMedDate not supplied

Cerebrospinal fluid absorption in the rabbit. Inner ear pathways.

Fifteen adult rabbits were perfused intrathecally with horseradish peroxidase (HRP) for 20-30 min under conditions that prevented any increase in cerebrospinal fluid (CSF) pressure. Histologic and ultrastructural examination of the cochlea disclosed HRP deposits along the cochlear and vestibular branches of the auditory nerve and beyond their ganglia, in a) epineural and perineural spaces; b) intraneural spaces reaching the membrane of myelinated axons via nodes of Ranvier; and c) extending beyond the epineurium into area lymphatics. HRP was also found in the basilar membrane, along with deposits in the scalae tympani, vestibuli, media and the spiral ligament. The endolymph also received HRP which followed vestibular nerve fibers and penetrated between sustentacular and hair cells of the cristae ampullaris and both maculae. HRP permeated interendothelial spaces lining the modiolus to reach the scala vestibuli lymphatics close to all the above areas were also permeated by HRP, but the inner tunnel was devoid of the marker.

Absorption↗
PubMedDate not supplied

High-resolution MR imaging of the cadaveric human spinal cord: normal anatomy.

The purpose of this study was to demonstrate the regional MR anatomy of a normal human spinal cord under near optimal conditions. A spinal cord and meninges were excised and segments from the cervical (C6), thoracic (T6), lumbar (L3), and sacral/cauda equina regions were examined on a 2-T MR system. By using a 2.5 x 2.0 cm solenoid coil and a multislice spin-echo sequence, we achieved a resolution of 58 microns in the readout direction and 117 microns in the phase-encode direction. Histological sections corresponding to the areas imaged by MR were retained and treated with stains that demonstrated the distributions of collagen (hematoxylin, phloxine, saffron), myelin (Luxol fast blue/H and E), or neuritic processes (Bielschowsky's). Subarachnoid vascular, white matter, and gray matter structures were demonstrated by MR and light microscopy. The resulting MR images and photomicrographs were correlated. Different signal intensities were observed in the gracile and cuneate fasciculi, and these differences were similar to the pattern seen with the myelin stain. Decreased signal intensity was present in the region of the spinocerebellar tracts. The anatomic detail demonstrated by this study was clearly superior to that shown by clinical MR examinations.

Cadaver↗
PubMedDate not supplied

MR imaging of the excised human brainstem: a correlative neuroanatomic study.

The purpose of this study was to examine an excised human brainstem with high-resolution MR imaging. The MR images were correlated with myelin-stained histologic specimens and standard anatomic descriptions. Structures visualized included nuclei and/or fibers of all the cranial nerves, with the exception of the trochlear nerve. The topography of the brainstem is discussed. Major tracts such as the corticospinal spinothalamic, spinocerebellar, medial and lateral lemniscus, and other ascending and descending tracts and intrinsic brainstem nuclei such as the olivary complex, pontine nuclei, red nucleus, and inferior and superior colliculi were identified. Functional neuroanatomy of the brainstem is reviewed. This neuroanatomic description and review of the complex MR anatomy of the brainstem should assist in the delineation of brainstem structures on MR imaging.

Adult↗