Alz-50 immunoreactivity in the central nervous system of adult rat and primate

Alz-50/Gallyas-positive lysosome-like intraneuronal granules in Alzheimer's disease and control brains

The Gallyas-Braak silver impregnation method revealed neurons containing well-defined intraneuronal granules in both Alzheimer's disease and normal control brains. The granules were immunostained prominently with the Alz-50 antibody and, to a lesser degree, with the tau-2 antibody, but not with other anti-tau antibodies examined. The areas of distribution of granule-containing neurons detected by the Gallyas-Braak method appeared to overlap with the reported main sites of subcortical distribution of neurofibrillary tangles. They, however, were not observed in the cerebral cortex, including the hippocampal region. The Alz-50 immunoreactive granules showed ultrastructural features similar to those of lysosomes or lipofuscin. These findings suggest that denatured tau might be degraded in lysosomes.

Injections of okadaic acid, but not beta-amyloid peptide, induce Alz-50 immunoreactive dystrophic neurites in the cerebral cortex of sheep

In an attempt to produce an animal model of neurofibrillary degeneration of the Alzheimer type, okadaic acid (a phosphatase inhibitor) and beta-amyloid peptide (1-40) were microinjected into the cerebral cortex of six adult sheep. After survivals varying from 1 day to 3 months, the injection sites and adjacent areas were evaluated using light microscopic immunocytochemistry. Near sites of implantation of crystalline okadaic acid, the Alz-50 monoclonal antibody stained twisted, dystrophic neurites. None of the beta-amyloid peptide injections caused neurofibrillary pathology. However, immunohistochemical analysis revealed no detectable beta-amyloid peptide remaining in the neuropil, even at 1 day, indicating rapid clearance of the beta-amyloid peptide. The induction of Alz-50 immunoreactive dystrophic neurites by okadaic acid in sheep represents a novel animal model of Alzheimer's neurofibrillary pathology.

Transgenic mice expressing APP-C100 in the brain

The classic hallmarks of Alzheimer's disease are the deposition of amyloid in plaques and in the cerebrovasculature, and the emergence of neurofibrillary tangles in neurons. The interplay between these two pathologic processes, on the one hand, and the degeneration of neurons and loss of cognitive functions on the other, remains incompletely understood. We have proposed that one crucial component of this interplay is a fragment of the Alzheimer amyloid protein precursor (APP) comprising the carboxyterminal 100 amino acids of this molecule, which we term APP-C100 (or, more simply, C100). This fragment, which comprises the 42-amino acid amyloid protein (A beta) and an additional 58 amino acids carboxyterminal to it, was found to be toxic specifically to nerve cells in vitro. We developed transgenic mouse models to test the hypothesis that APP-C100 causes Alzheimer's disease neuropathology. APP-C100 was delivered to the mouse brain via a transgene expressing C100 under the control of the dystrophin brain promoter. These transgenic animal models for the action of APP-C100 in the brain exhibited some of the neuropathological features characteristic of Alzheimer disease brain. The animal models that we have created can be used to test hypotheses concerning the mechanism by which C100 interacts with a neuronal receptor to kill neurons.

Widespread appearance of Alz-50 immunoreactive neurons in the human brain with cerebral infarction

BACKGROUND AND PURPOSE

Tau-like immunoreactivity is known to develop in neurons under some experimental conditions simulating ischemia. The purpose of this study is to investigate the expression of tau-like immunoreactivity in the human brain after ischemic insult.

METHODS

A series of autopsied human brains with or without ischemic lesion were investigated with immunohistochemistry (Alz-50, anti-tau, and anti-ubiquitin) and with silver-staining methods (Gallyas and Bodian methods).

RESULTS

Punctate immunoreactivity to Alz-50 was visualized in the cytoplasm not only of the neurons in and around the ischemic lesion but also of the neurons free from classic ischemic changes around the necrosis. Some of the neurons around the ischemic lesion were stained by the Gallyas method. Immunostaining with anti-tau and anti-ubiquitin antibodies and the conventional Bodian method failed to visualize these neurons.

CONCLUSIONS

The widespread appearance of Alz-50 immunoreactive neurons during the ischemic process signifies that tau-related proteins may be related to ischemic necrosis, but the lack of neurofibrillary tangles morphologically distinguishes ischemic development of tau-related proteins from the neurofibrillary degeneration in Alzheimer's disease.

Alz-50 recognizes epitopes in primary sensory fibres and in neurons of the substantia gelatinosa of the spinal cord. An ultrastructural study in the rat

The monoclonal antibody Alz-50 has been proposed as a marker for cellular pathological changes in Alzheimer's disease. However, it has been reported that this antibody also reacts with specific epitopes in normal individuals. Furthermore, intense Alz-50 immunoreactivity has been recently described in the hypothalamus and spinal cord of rat and monkey. In the present study, we analysed the distribution pattern of Alz-50 immunostaining in the spinal cord of the adult rat. Using light microscopy, immunostained fibres and varicosities were detected mainly in laminae I-II, although some immunostaining lamina I and the outer two thirds of lamina II. The varicosities appeared either scalloped or dome-shaped and contained numerous agranular synaptic vesicles and a few dense-core vesicles. Most varicosities were presynaptic to dendrites. A few immunostained cell bodies and dendrites were also observed, but glial cells were never immunostained. Some ultrathin sections were processed for postembedding immunogold detection of calcitonin gene-related peptide and GABA immunoreactivities. Most of the varicosities which were immunoreactive for Alz-50 also showed calcitonin gene-related peptide immunoreactivity. In contrast, GABA immunoreactivity was never co-localized with Alz-50 immunoreactivity. These results indicate that, in the superficial dorsal horn, the epitope recognized by the Alz-50 antibody is located mainly, but not exclusively, in primary sensory fibres.

Tau protein immunolocalization in fetal and adult human spinal cord

In the present study, the monoclonal antibody Alz-50 has been used to determine and compare the immunohistochemical localization of phosphorylated tau proteins in the developing and normal adult spinal cord. At all stages of fetal life Alz-50 fiber immunoreactivity was observed in the dorsal roots, in the dorsal and dorsolateral funiculi, and in restricted regions of the dorsal horn. Alz-50 immunoreactivity was also demonstrated in the dorsal root ganglion neurons. In the adult spinal cord a consistent pattern of Alz-50 fiber immunoreactivity was localized in the superficial layers of the dorsal horn (lamina I and II) but not in dorsal and dorsolateral funiculi and in the dorsal root ganglion. Comparable results in fetal specimens have been obtained employing PHF-1, a monoclonal antibody generated against paired helical filament proteins from Alzheimer brains, while no significant immunostaining for PHF-1 was observed in the adult spinal cord. In addition, the staining with monoclonal and polyclonal anti-tau antibodies overlapped with that of Alz-50. The transient, selective pattern of Alz-50 and PHF-1 immunoreactivity may disclose some relevant functions of tau proteins during somatosensory pathway development.