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Biomedical subjects

R P Manzo

Publications and source records attributed to R P Manzo.

6 recordsLinked to original sources
PubMed1994

Direct in vivo observation of transventricular absorption in the hydrocephalic dog using magnetic resonance imaging.

RATIONALE AND OBJECTIVES: A model of chronic noncommunicating hydrocephalus in canines was developed, and gadolinium-DTPA (Gd-DTPA)-enhanced magnetic resonance imaging, physiologic and morphologic studies were performed to investigate transventricular absorption of cerebrospinal fluid. METHODS: Chronic hydrocephalus was induced in 12 mongrel dogs by injection of a silastic mixture into the prepontine cisterns. Ventricular pressure was measured during the development of hydrocephalus, and lateral ventriculo-ventricular perfusions with Gd-DTPA were performed under controlled conditions during serial magnetic resonance imaging studies. RESULTS: Hydrocephalus developed over an average of 129 +/- 24 days after induction, and the intraventricular pressure increased from an initial level of 14 +/- 4 cm H2O to a stabilized plateau of 25 +/- 5 cm H2O. Increased signal intensity in the brain matter, as seen on magnetic resonance images of chronic hydrocephalic dogs perfused with Gd-DTPA in the lateral ventricles, was consistent with the presence of the contrast agent in the periventricular extracellular space. This increased signal intensity was not observed in control animals. CONCLUSIONS: These results provide direct evidence of transventricular absorption in chronic hydrocephalus.

Absorption↗
PubMed1988

Cerebrospinal fluid absorption in the rabbit. Optic pathways.

Fifteen rabbits were intrathecally perfused with horseradish peroxidase at normal cerebrospinal fluid pressures. Horseradish peroxidase was found in the subarachnoid space around the optic nerve; it permeated the pia and penetrated within the nerve, occupying extracellular spaces between myelinated axons and glial cells up to the area of the lamina cribrosa. Horseradish peroxidase also crossed the perineural sclera and the border tissue of Elschnig to spread into the choroid where it was mostly seen within choriocapillaris, venules, and veins crossing through interendothelial spaces. "Bulk" cerebrospinal fluid absorption in the eye appears to occur through venous drainage in the choroid and SAS.

Animals↗
PubMedDate not supplied

Diagnosis of cerebral ventriculomegaly in normal adult beagles using quantitative MRI.

The brain of 17 asymptomatic normal adult beagles was evaluated with magnetic resonance imaging. Lateral ventricular size was quantified using computer algorithms. In beagles with large ventricles, contrast medium was introduced into the cerebellomedullary cistern to determine whether obstructive hydrocephalus was present. Total lateral ventricular volume ranged from 77 mm3 to 11,726 mm3. Based on Gd-DTPA diffusion, the CSF flow pattern was considered normal and normal neural morphology was seen using electron microscopy. Results suggest a high incidence of clinically asymptomatic ventriculomegaly in normal adult beagles.

Animals↗
PubMedDate not supplied

Cerebrospinal fluid absorption in the rabbit: olfactory pathways.

Twenty rabbits were intrathecally perfused with horseradish peroxidase (HRP) without increasing the cerebrospinal fluid (CSF) pressure. Histologic and ultrastructural studies of the olfactory nerve and nasal mucosa showed HRP along the space between peri- and epineurium down to the smaller nerve branches in the mucosa. Within the mucosa, HRP leaked out from the epineurium and flowed into: (a) lymphatic vessels; (b) mucous glands and ducts; (c) intercellular spaces of the nasal pseudostratified nasal epithelium; and (d) venules. These findings could account for "bulk" flow CSF absorption into the lymphatic system, the nasal cavity, and to a lesser degree, the venous system; also explain CSF rhinorrhea in man and experimental animals; as well as lymphatic drainage of CSF into cervical lymph nodes.

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↗