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Biomedical subjects

R L Friede

Publications and source records attributed to R L Friede.

At least 91 records · Page 5Linked to original sources
PubMed1980

Computed tomography in neuronal ceroid lipofuscinosis.

The computed tomography (CT) findings in a verified case of neuronal ceroid lipofuscinosis (NCL) are presented. CT revealed diffuse and severe cerebral atrophy, reflected by generalized subarachnoid space enlargement and symmetric ventricular dilatation. There was no evidence of abnormalities of the white matter. The CT features in our case of NCL correspond perfectly with the neuropathologic changes of the disease mentioned in the literature. Furthermore, CT is of considerable help in differentiating between those inherited metabolic brain diseases characterized primarily by white matter involvement and those presenting predominantly with changes of grey matter.

Ceroid↗
PubMed1980

Hypotensive brain stem necrosis or cardiac arrest encephalopathy?

Selective symmetrical necroses of many tegmental brain stem nuclei including motor cranial nerve nuclei, superior and inferior colliculi, cuneate and gracilis nuclei, and others are known as hypotensive brain stem necrosis (Gilles 1969). We found such lesions in eight infants and seven adults. Examination of their clinical records revealed a well documented episode of cardiac arrest in each case. Cardiac output was restored in all but one patient 5 min to 4 h after the beginning of resuscitation. All patients remained comatose in a decerebrate state up to their death 17 h to 4 weeks after admission. Our findings and a review of the literature indicate that this type of lesion relates specifically to cardiac arrest. The term "hypotensive brain stem necrosis"is a misnomer and should be replaced by the term "cardiac arrest encephalopathy".

Adolescent↗
PubMed1980

The precise geometry of large internodes.

The interrelations, in each given internode, between internodal length, axon caliber, axoplasmic volume and several parameters of sheath thickness were studied in a set of 37 large internodes from the sciatic nerve of the German shepherd dog, using multiple electron-microscopic measurements of isolated fibers. Internodal length varied in a nonlinear relation with axon caliber. Nonlinear relations were also found for the number of lamellae in the sheath as related to either axon caliber or to internodal length, particularly for large internodes: the deviations observed for axon caliber (thick fibers had fewer myelin lamellae than would correspond to axon caliber) were the opposite of for internodal length (thick fibers had more lamellae than would correspond to internodal length). A near linear relationship was found if the volume of myelin per internode was related to both the length and the circumference of the axon segment ensheated by it, i.e., axolemmal surface area. The deviations in the proportions of large internodes probably indicate the existence of upper limits of internodal growth conditioned by the enormous metabolic demands placed on the individual Schwann cell by the growth of internodes beyond 1.5--2 mm length or 100 thousand micrometer3 of myelin, respectively. The demands on myelin metabolism from unabated internodal growth and the resultant logistic problems of the Schwann cells are demonstrated from measurement of observed internodes and calculations of extrapolated growth.

Animals↗
PubMed1980

The fine structure of stumps of transected nerve fibers in subserial sections.

The proximal stumps of five rat sciatic fibers, transected 72 hr earlier, were reconstructed on the basis of morphometry in subserial electron micrographs of isolated fibers. Three fibers showed extensive axon sprouting; 2 had no sprouts but were excessively swollen. The total volume of axoplasm in the axon swellings approximated the volume of axoplasm in all sprouts of any given fiber. Axonal swelling therefore may ensur when sprouting is frustrated. Axon sprouts originated mostly at nodes from where they descended or ascended along the fiber, running within its lamina basalis. Sprouting began soon after injury, usually within the first day. Counts of microtubules showed an approximately 10-fold increase in the total number of tubules per fiber toward the injured end. Schwann cells showed asymmetric hypertrophy, having distinctly more cytoplasm distally than proximally to the nucleus. The increase in Schwannian cytoplasm occurred roughly pari-passu with the increases in axoplasm. Hypertrophy of Schwann cells was associated with cytoplasmic islands or strands having an extremely variable content of organelles. Such islands of Schwannian cytoplasm may be confused with axon sprouts. Retraction of the myelin sheaths at nodes results in fiber profiles suggestive of partial demyelination. Retraction of nodal pseudopodia produces redundant loops of lamina basalis. Migratory cells are seen outside the fibers or underneath their lamina basalis having a preference for nodal regions or for the fiber stump. They behave differently toward axon or myelin: they encompass axon sprouts as do immature Schwann cells; simultaneously the same cell may invade myelin sheaths like a macrophage. Other curious overlaps of degenerative and regenerative phenomena were noted, including an axon sprout tunneling through the lumen of the sequester of the myelin sheath of its parent axon.

Animals↗
PubMed1979

A quantitative study of the composition of cerebellar cortical dysplasias.

The areas of molecular and granular layers in four large cerebellar cortical dysplasias were measured with the planimeter and the Purkinje cells were counted. There was a relative deficit of molecular layer and a still greater deficit of Purkinje cells in three of the four dysplasias. The fourth one had normal numbers of Purkinje cells per molecular layer and a relative deficit of granular layer. These abnormal proportions in the composition of a dysplasia may relate to the timing of its origin.

Aged↗
PubMed1979

Striato-nigral astrocytic melanization.

Abnormal pigmentation was found in the striatum, pallidum and substantia nigra of two unrelated patients. Both had suffered from debilitating joint disease; there was no evidence of a progressive neurologic disorder. The pigment was localized in astrocytes and had the histochemical and electron microscopic features of melanin. The tissue changes suggest an anomaly of catecholamine metabolism either endogenous or induced by a still unknown exogenous factor.

Aged↗
PubMed1979

Production of myelin by neoplastic cells.

Formation of myelin sheaths by neoplastic cells was found in a spinal ganglioneuroma. All phases of initial myelination were observed including the formation of a mesaxonal spiral and the fusion of its lamellae into a major dense line. A unique aspect of neoplastic myelin formation was the formation of sheaths around bundles of extracellular fibrils rather than axons or cell processes. Formation of myelin sheaths around extracellular material has never been observed before. The findings have implications on the mechanisms controlling initial myelination.

Axons↗
PubMed1979

Perisulcal infarcts: lesions caused by hypotension during increased intracranial pressure.

A pattern of cortical necrosis surrounding the cerebral sulci and similar to ulegyria was found in 5 patients. The lesions were widely disseminated in all parts of the hemispheric cortex, affecting mostly the deep cortex of several adjacent sulci. They were hemorrhagic in 3 patients, ischemic in the others. Each patient had suffered a severe brain injury and became comatose thereafter. Increased intracranial pressure was evident from clinical findings, necropsy changes, or both. While in coma, each patient had at lease one episode of hypotension. The data suggest that perisulcal infarcts are a manifestation of diminished vascular perfusion during a period of increased intracranial pressure.

Adult↗
PubMed1979

Fine structure of arachnoid cysts.

Recent studies of the fine structure of the cranial meninges of laboratory animals and man have shown that there is no subdural space. The latter is formed artificially by the tendency of meningeal tissues to cleave along a collagen-free zone, the dura-arachnoid interface layer. This layer is composed of an outer zone of dural border cells and an inner arachnoid barrier layer. The fine structure of nine arachnoid cysts was studied to determine the derivation of the cyst's wall from the various components of normal human meninges. A cleaved dura-arachnoid interface layer covered only the dome of the cyst where the latter had abutted the dura mater. The interface layer did not partake in forming the cyst's wall. The dominant phenomenon of the cyst's wall was an absence of the normal trabeculation of the subarachnoid space, the trabecules being replaced by tightly packed collagen fibrils and a few scattered cells in between. Some cells were layered discontinuously at the inner face of the cyst wall, but there was no organized inner lining. No evidence was found for either a tight sealing of the extracellular spaces in the cyst's wall, nor for the existence of an active transcellular fluid movement.

Aged↗
PubMed1978

Postencephalitic porencephaly, hydranencephaly or polymicrogyria. A review.

Twenty necropsy cases of the association of fetal encephalitis with porencephaly, hydranencephaly or polymicrogyria were reviewed including 5 from the authors' material. The latter include a basket brain, a porencephalic necrosis of recent date and a polymicrogyria in the formative state. The supratentorial lesions are often associated with cerebellar cortical dysplasias. The pathogenetic interdependence of encephalitis and hemispheric defects or malformation is discussed. Examples are given in which the infection appears to be secondary to a pre-existent hemispheric lesion. For others the hemispheric lesions appear to be secondary to encephalitis. In these the encephalitis may produce secondary lesions by a variety of pathogenetic mechanisms.

Brain↗
PubMed1978

Dural involvement in rheumatoid arthritis.

Involvement of the cranial dura in rheumatoid arthritis is rare; a new case of this complication is added to the four recorded instances. Dural involvement in rheumatoid arthritis may occur in the absence of other rheumatoid lesions of the CNS; it appears to take a clinically uneventful course and does not seem to represent a factor predisposing to the development of chronic subdural hematoma.

Aged↗
PubMed1978

How do axons control myelin formation? The model of 6-aminonicotinamide neuropathy.

Injection of 6-aminonicotinamide into young rats produces a peculiar neuropathy characterized by selective swelling and disruption of the layer of Schwann cell cytoplasm lining the inner surface of the myelin sheath. This layer increases greatly in volume, compressing the axon and distending the myelin sheath. Morphometry of such swollen fibers discloses that the amount of myelin in the distended sheaths is considerably greater than would correspond to the size of the axons, even if axonal compression is accounted for. The data favor the concept that sheath growth is stimulated by non-specific distension of the myelin sheath from inside.

6-Aminonicotinamide↗
PubMed1978

The organization of endoneural collegen in peripheral nerves as revealed with the scanning electron microscope.

Transmission electron microscopy of isolated nerve fibers of rat sciatic nerve and scanning microscopy of small groups of fibers reveal that the majority of collagen fibrils form tightly woven cuffs around individual nerve fibers. Only a small fraction of the fibrils is not associated with individual nerve fibers and forms a loose, wide-meshed net between them. These observations reconfirm the pre-electron-microscopic concept of a sheath of Key and Retzius or of Plenk and Laidlaw, respectively.

Animals↗
PubMed1978

Dystopic myelination with hypertrophy of pyramidal tract.

In a case of hypertrophy of the pyramidal tract the cross section of the hypertrophic pyramids was 174% of controls with an increase (148%) in the total population of myelinated fibers. However, there was no commensurate increase in the density of Betz cells. Confined to the hypertrophic tract there was a peculiar anomaly consisting of tubes of thick myelin sheaths that encompassed columns of glial nuclei instead of axons. This type of change, along with the clinical data, may indicate that the lesion originated in the perinatal period when myelin formation is in progress and is susceptible to derangement.

Cell Count↗