A biochemical and histochemical study of glutamic oxalacetic transaminase activity of rat hepatic mitochondria fixed in situ and in vitro.

Rat liver perfused in situ briefly with a glutaraldehyde-formaldehyde mixture was homogenized in isotonic sucrose. The mitochondria, isolated from a homogenate of the perfused liver by differential centrifugation, assumed a slender and compact appearance similar to those often seen in an intact cell. The glutamic oxalacetic transaminase (GOT) activity of this mitochondrial fraction survived an additional formaldehyde fixation and was studied by biochemical and histochemical methods. The biochemical assay of the enzyme activity revealed that the activity was only slightly less than that of an unfixed mitochondrial fraction. The reaction product due to mitochondrial GOT activity was found to be localized to the cristae, as had been demonstrated in an intact liver cell. GOT activity of the mitochondrial fraction isolated from fresh liver tissue homogenate in 0.25 M sucrose was inactivated readily by either glutaraldehyde or formaldehyde and was no longer demonstrable by biochemical and histochemical methods after fixation.

Electron microscope studies of glutamic oxalacetic transaminase in rat liver cell.

Liver tissue of the rat, fixed in glutaraldehyde and formaldehyde, was incubated in a medium which consisted of 20 mML-aspartic acid, 2 mM alpha-ketoglutaric acid, 50 mM imidazole and 6 mM lead nitrate at pH 7.2-7.4. The electron-opaque precipitates, due to glutamic oxalacetic transaminase activity in liver cells, were found to be localized to the cristae and surface membranes of the mitochondria, the limiting membrane of the microbodies, and the nuclear membrane. Sucrose storage and trauma resulted in altered morphology and diminished final product intensity in mitochondria, but the microbody enzyme activity disappeared completely under these conditions. These distinctive responses of enzymatic activity are considered to indicate a difference in either the enzyme protein or its membrane attachment to these two sites. The use of a buffered dehydrating ethanol series to prepare tissue blocks for electron microscopy appeared to result in more precise intracellular localization of enzymatic reaction product.

Neuronal argyrophilia and phosphorylated neurofilament accumulation secondary to deafferentation.

This work tests the hypothesis that deafferentation caused by experimental brain lesions leads to the appearance of perikaryal argyrophilia and the accumulation of phosphorylated cytoskeletal proteins which are potential precursors for neurofibrillary tangle formation. Destructive lesions of the ventral tegmental area, the septum of the medial forebrain and the entorhinal cortex, when combined with systemic administration of a D-1 dopamine receptor antagonist, produced transsynaptic changes in neurons of the hippocampal formation in the midbrain. Abnormally phosphorylated neurofilament protein was demonstrated immunohistochemically in the cytoplasm of mesencephalic pyramidal neurons, particularly in the red nucleus. These same neurons also developed cytoplasmic argyrophilia in Bielschowsky histologic preparations. Although distinct neurofibrillary tangles were not produced with this paradigm, both the protein immunoreactivity and argyrophilia were arranged in cytoplasmic linear arrays. The structural changes induced in this experimental model may be an important preliminary stage for neurofibrillary tangle formation.

Correlative assay of computerized cranial tomography CCT, water content and specific gravity in normal and pathological postmortem brain.

An assay of water content and specific gravity in normal and pathological autopsy brain has been correlated with CCT attenuation values obtained just prior to brain cutting. Formalin fixation does not alter normal values so that fixed brain appears to be suitable for this type of study. Low attenuation values in CCT correlate better with changes in specific gravity, rather than water in infarcts, but they have a close relationship to water content in edema. The high water content in infarcts of the white matter reveals a striking disparity in fluid control between cortex and white matter, which has not been emphasized in experimental studies. Water movement within and around blood clots has been discussed.

Historical aspects of normal and abnormal brain fluids. II. Hydrocephalus.

A history of internal hydrocephalus from Vesalius to the present has been presented. Several intriguing aspects of hydrocephalus have been explored, including the existence of this disorder before tha 16th century and the possibility of medical management. The exciting promise and discouraging failure of experimentally devised choroid plexectomy has been recounted. Finally, the remaining enigma of spontaneous arrest has been discussed.

Historical aspects of normal and abnormal brain fluids. III. Cerebral edema.

The early life, death, and revival of the concept of cerebral edema are discussed. This unusual sequence has been related to a clinical syndrome, a vascular hypothesis, a unique brain circulation, and a new investigative technique: electron microscopy.

The association of ventral tegmental area histopathology with adult dementia.

Six cases of adult dementia with mesolimbic pathology are reported. The core clinical syndrome consists of parkinsonism, progressive dementia, and behavioral disturbances (generally depression). The histopathologic findings uniformly include a loss of pigmented neurons in the ventral tegmental area plus neurofibrillary tangles and/or cell loss in the entorhinal cortex and pyramidal cell layer of the hippocampus (perforant pathway). Neuronal depletion in the ventral tegmental area frequently is associated with similar cell loss in the adjacent substantia nigra and in the locus ceruleus. The development of neurofibrillary tangles in the perforant pathway occurs in the absence of senile plaques and is possibly related to diminished dopaminergic input.

The effect of size, histologic elements, and water content on the visualization of cerebral infarcts.

We correlated the radiologic and pathologic examination of 13 human brains, analyzing the size, different histologic elements, and water content in 40 ischemic and hemorrhagic infarcts. Acute infarcts appear in the computerized cranial tomographic (CT) image as low density areas due to high content of fluid, however, a histological-chemical correlation is not concomitant. The addition of blood in hemorrhagic infarcts may result in a normal CT image. Subacute infarcts appear as low density areas, with lower attenuation values due to the presence of large amounts of lipids. Subacute lesions with prominent mineral deposits may be negative on CT scan. Chronic infarcts also appear as low density areas due to cavitation and residual fats. Attenuation values are slightly higher than those of subacute infarcts, possibly due to gliosis. Infarcts smaller than 2 cm in diameter are usually not visualized.

Amyotrophic lateral sclerosis with ophthalmoplegia. A clinicopathologic study.

Ophthalmoplegia is rarely observed in patients with amyotrophic lateral sclerosis (ALS). We describe a patient with ALS in whom ophthalmoplegia, initially appearing midway in her course, progressed to total paralysis of extraocular movements by the time of death. In addition to the usual postmortem findings of ALS in the brain stem and spinal cord, there was extensive neuronal loss and gliosis involving the caudal portions of the dorsal and intermediate components of the oculomotor nuclei, the caudal part of the trochlear nuclei, and the abducens nuclei. This represents the first detailed report of the findings in the nuclei of cranial nerves III, IV, and VI in a patient with ALS and ophthalmoplegia.

Congenital retardation and central motor defect with later evolution of seizure disorder, orofacial dysplasia, and amyotrophy. A clinicopathologic report.

Retarded mental and motor development was observed during the first year of life of a full-term female who had been delivered with difficulty. Generalized psychomotor seizures and dysplastic "acromegalic" facial changes began to develop when she was 8 years old, and generalized amyotrophy developed over the next several years. The course was generally progressive, and she died at age 31. A variety of clinical laboratory studies were nondiagnostic. Autopsy findings showed normal brain weight and normal-appearing cerebral hemispheres, a peculiar atrophy of the inferior portion of the cerebellar hemispheres, a demyelinating process in the dorsal columns of the cervical and thoracic spinal cord, and lateral column and motor neuron degeneration. The pathogenesis of the syndrome is undetermined.

Analysis of the prion protein gene in thalamic dementia.

Thalamic degenerations or dementias are poorly understood conditions. The familial forms are (1) selective thalamic degenerations and (2) thalamic degenerations associated with multiple system atrophy. Selective thalamic degenerations share clinical and pathologic features with fatal familial insomnia, an autosomal dominant disease linked to a mutation at codon 178 of the prion protein (PrP) gene that causes the substitution of asparagine for aspartic acid (178Asn mutation). We amplified the carboxyl terminal coding region of the PrP gene from subjects with selective thalamic dementia or thalamic dementia associated with multiple system atrophy. Three of the four kindreds with selective thalamic dementia and none of the three kindreds with thalamic dementia associated with multiple system atrophy had the PrP 178Asn mutation. Thus, analysis of the PrP gene may be useful in diagnosing the subtypes of thalamic dementia. Moreover, since selective thalamic dementia with the PrP 178Asn mutation and fatal familial insomnia share clinical and histopathologic features, we propose that they are the same disease.

Denervation induced abnormal phosphorylation in hippocampal neurons.

This study demonstrates that combined dopaminergic and cholinergic denervation of the hippocampus results in the appearance of morphologically altered, Tau reactive, apical dendrites of granule cells in the rat dentate gyrus. The denervated granule cells and their apical dendrites also display immunoreactivity to a mitogen-activated protein kinase, ERK-1, and also evidence of abnormal phosphorylation of these dendrites as revealed by SMI-31 immunoreactivity. Dopaminergic denervation alone also causes mitogen activated protein kinase reactivity without the Tau-reactive apical dendrities. These results suggest an analogy to synaptophysin loss and the appearance of dendritic threads described in Alzheimer's disease (AD), as an early stage in the formation of neurofibrillary tangles (NFT). This is the first animal model in which abnormal phosphorylation of Tau has been shown to be produced experimentally in vivo.

Hippocampal pyramidal cell response to 6-hydroxydopamine lesions of the rat ventral tegmental area.

The occurrence of neurofibrillary tangles (NFT) in the perforant pathway in association with dopaminergic cell loss in the ventral tegmental area (VTA) in human mesolimbic dementia, raises the possibility that denervation is a cause of NFT formation. This was tested in the rat by lesioning dopaminergic neurons which project to the hippocampus from the ventral tegmental area by means of stereotaxic injections of 6-hydroxydopamine. This resulted in the appearance of immunoreactivity to the paired helical filament protein plus an increase of tau and MAP-2 proteins in pyramidal neurons of CA-1 and CA-2. These neuronal responses to dopaminergic denervation are consistent with a precursor stage to NFT development.

T-lymphocyte function in Alzheimer's disease.

T-lymphocyte function in Alzheimer's disease (AS) was evaluated by means of delayed type hypersensitivity (DTH) and mitogen responsiveness using concanavalin A (Con A) and BCG vaccine as stimulators. DTH and the response to Con A was significantly lower in AD than in normal aging. The Con A response included one group in which the thymidine uptake was lower than the minimum normal response while another group was within the normal range. This subset could account for the inconsistency in previous reports of T-cell function in AD.

Immunoreactive changes resulting from dopaminergic denervation of the dentate gyrus of the rat hippocampal formation.

The hypothesis that dopaminergic denervation is a factor in the development of hippocampal neurofibrillary tangles was tested in the rat with bilateral stereotaxic 6-hydroxydopamine (6-OHDA) lesions of the ventral tegmental area (VTA). This led to the postsynaptic appearance of cytoplasmic immunoreactivity to ubiquitin in neurons of the dentate gyrus. An additional postsynaptic morphologic abnormality was seen when the animals were pretreated with the D1 dopaminergic antagonist SCH 23390 and the VTA lesions were combined with septal lesions affecting cholinergic and GABAergic neurons projecting to the dentate gyrus. These changes consisted of a loss of dendritic microtubule associated protein (MAP-2) and tau immunoreactivity and a prominence of remaining dendrites in the molecular layer of the dentate gyrus. Additional investigation will be needed to determine if these transynaptic changes in dentate neurons, resulting from denervation, represent a precursor stage to neurofibrillary tangle development.

Tyrosine hydroxylase-like (TH) immunoreactivity in human mesolimbic system.

A practical methodology has been described for the use of human postmortem brain tissue in both tyrosine hydroxylase and dopamine beta-hydroxylase immunohistochemistry in which in situ perfusion with paraformaldehyde is followed by immersion fixation in Bouin's fixative. These studies indicate that TH-like immunoreactive fibers and terminals are not uniformly distributed in the human hippocampal complex. A distinctive lesser innervation is noted for the structures that compose the perforant pathway and may be important for the predilection of these areas for pathological change particularly as occurs in Alzheimer's disease.

Adult dementia: history, biopsy, pathology.

The historical events in the evolution of Alzheimer's disease are reviewed, including the initial description by Alois Alzheimer and the subsequent controversy regarding the nosological specificity of this entity. The similarity of senile dementia and Alzheimer's disease is emphasized. The basis for the modern concept of Alzheimer's disease as premature or accelerated aging is included in the review. The pathological correlates of the major categories of adult dementia have been described. The traditional criteria of neurofibrillary tangles and senile plaques have been re-evaluated using the current insight into these changes afforded by electron microscopy and biochemistry. The significance of amyloid has been described because it occurs within the senile plaque and also as the essential component of congophilic angiopathy. The new information regarding neuronal cell counts and the loss of choline acetyltransferase has been evaluated in terms of an indication of a pathogenic mechanism of Alzheimer's disease. The current understanding of normal pressure hydrocephalus, Creutzfeldt-Jakob disease, and multi-infarct dementia has been described. Brain biopsy in dementia has been described as having diagnostic, research, pathogenic, and prognostic value. The precautions involving the performance and handling of the biopsy have been stressed, particularly because these procedures involve conditions of possible slow virus etiology. The polemic for Alzheimer's disease as aging or slow virus infection has been summarized. At this time a consideration seems justified that Alzheimer's disease is an age-related, slow virus disease due to a hitherto unknown immune defect. Aging as an etiological agent must be clarified before Alzheimer's disease, in any form, can be considered to be an inevitable consequence of longevity.

Delayed hypersensitivity in Alzheimer's disease following BCG immunostimulation.

Forty-four patients with Alzheimer's disease were evaluated for delayed hypersensitivity responses using five ubiquitous antigens. Compared with a nondemented age-matched population, these patients evidenced a large number of deficient responses, especially in the zero-response group. Twenty-three patients were randomly selected for immunostimulation using BCG vaccine. The skin tests were repeated 2 weeks after a series of four weekly intradermal injections of BCG. Only 2 of 13 nonresponsive patients failed to convert at least one negative result into a positive response, and seven became normal.

The pathogenetic significance of congophilic angiopathy.

Congophilic angiopathy has been separated into two forms. A primary vasculopathy is described in which amyloid deposition is the initial morphological brain change and is of pathogenetic importance in the development of dementia or brain hemorrhage. Another form occurs in Alzheimer's disease and is incidental to the brain damage resulting from senile plaques.