Biomedical subjects

Y C Tung

Publications and source records attributed to Y C Tung.

32 records · Page 2Linked to original sources

PubMed1986

Microtubule-associated protein tau. A component of Alzheimer paired helical filaments.

Microtubule-associated protein tau was purified from bovine brain microtubules by either (1) phosphocellulose chromatography, (2) heat treatment at pH 6.4, (3) heat treatment at pH 2.7, (4) heat treatment at pH 2.7 followed by extraction with perchloric acid and precipitation with glycerol, or (5) by precipitation with ammonium sulfate followed by extraction with perchloric acid. All of these tau preparations reacted specifically with antibodies to Alzheimer paired helical filaments. Affinity purified antibodies to tau labeled both Alzheimer neurofibrillary tangles and plaque neurites but not amyloid in Alzheimer brain tissue sections and labeled paired helical filament polypeptides on Western blots. Human brain tau and paired helical filament polypeptides co-migrated on sodium dodecyl sulfate-polyacrylamide gels. These results suggest that tau is a major component of Alzheimer paired helical filaments.

Alzheimer Disease↗

PubMed1986

Abnormal phosphorylation of the microtubule-associated protein tau (tau) in Alzheimer cytoskeletal pathology.

A monoclonal antibody to the microtubule-associated protein tau (tau) labeled some neurofibrillary tangles and plaque neurites, the two major locations of paired-helical filaments (PHF), in Alzheimer disease brain. The antibody also labeled isolated PHF that had been repeatedly washed with NaDodSO4. Dephosphorylation of the tissue sections with alkaline phosphatase prior to immunolabeling dramatically increased the number of tangles and plaques recognized by the antibody. The plaque core amyloid was not stained in either dephosphorylated or nondephosphorylated tissue sections. On immunoblots PHF polypeptides were labeled readily only when dephosphorylated. In contrast, a commercially available monoclonal antibody to a phosphorylated epitope of neurofilaments that labeled the tangles and the plaque neurites in tissue did not label any PHF polypeptides on immunoblots. The PHF polypeptides, labeled with the monoclonal antibody to tau, electrophoresed with those polypeptides recognized by antibodies to isolated PHF. The antibody to tau-labeled microtubules from normal human brains assembled in vitro but identically treated Alzheimer brain preparations had to be dephosphorylated to be completely recognized by this antibody. These findings suggest that tau in Alzheimer brain is an abnormally phosphorylated protein component of PHF.

Alzheimer Disease↗

PubMed1985

Alzheimer paired helical filaments: identification of polypeptides with monoclonal antibodies.

Paired helical filaments (PHF) were isolated from autopsied brain of cases of Alzheimer dementia, and their polypeptides were identified with monoclonal antibodies to PHF by Western blots. The PHF polypeptide profile consisted of several bands with a size difference of less than 5 kilodalton (kDa) between adjacent bands; the most prominent bands were in the 45-62 kDa region. These PHF polypeptides were also labeled with tangles reactive antisera to microtubules from normal brain but had electrophoretic patterns different from those of microtubules and neurofilaments. These studies define the molecular weight profile of PHF polypeptides and suggest that they might originate from normal brain proteins.

Aged↗

PubMed1985

Alzheimer paired helical filaments: cross-reacting polypeptide/s normally present in brain.

Antisera to microtubule-enriched fraction from normal human brain (anti-MT sera) label neurofibrillary tangles and neurites of neuritic (senile) plaques in brain sections of cases with Alzheimer disease/senile dementia of the Alzheimer type (AD/SDAT); the plaque core amyloid is not labeled. These anti-MT sera label both tangles in tissue sections and smears of isolated tangles which had been extracted with sodium dodecyl sulfate (SDS) to remove impurities trapped in between the paired helical filaments (PHF). The tangle labeling of anti-MT sera is eliminated on their absorption both with microtubule-enriched fractions from human and animal brain and with the isolated PHF. Neurofilament triplet, actin, myosin, keratin, or fibroblasts do not absorb the tangles staining antibodies. Furthermore, antisera containing antibodies to tubulin, microtubule-associated high mol. wt. polypeptides (MAPS), neurofilament triplet, and the 50,000 mol. wt. contaminant of CNS neurofilament preparations do not label tangles. On immunoblots of SDS-polyacrylamide gels of isolated PHF anti-MT sera label some of the same polypeptides identified with antisera to PHF; affinity-purified antibodies to tubulin used as a control do not label any PHF polypeptide on the immunoblots. The anti-MT sera, when preabsorbed with the PHF polypeptides eluted from SDS-polyacrylamide gels, do not label tangles. These studies demonstrate that a polypeptide/s cross-reactive with Alzheimer PHF is indeed normally present in brain and that it is different from tubulin, neurofilament triplet, actin, myosin, vimentin, and keratin.

Actins↗

PubMed1984

Alzheimer paired helical filaments: immunochemical identification of polypeptides.

Antisera to isolated Alzheimer neurofibrillary tangles (ANT) of paired helical filaments ( PHF ) were raised in rabbits. These anti- PHF sera immunolabeled both ANT in sections of Alzheimer hippocampus and ANT which were isolated and extracted with sodium dodecyl sulfate (SDS). The immunostaining of ANT in tissue sections was removed by absorption of the anti- PHF serum with small amounts of PHF and also with 40-fold the amount of a fraction prepared identically from normal brain; neurofilament and brain microtubule preparations used at the same concentration as the normal brain control fraction did not eliminate the tangle staining. Furthermore, the tangle staining was also not removed with glial filaments or actin and myosin filaments. No labeling of the neurofilaments of axons and cerebellar basket fibers by anti- PHF sera was observed in tissue sections from non-neurologic brain. On paper blots of SDS-polyacrylamide gels anti- PHF serum reacted with neither polypeptides of the normal brain control fraction nor major microtubule and neurofilament polypeptides. However, the immunoblots of PHF preparations with the anti- PHF serum revealed staining of several polypeptide bands in the 45,000-70,000 molecular weight (MW) region, material on top of the gel and diffuse staining of the high MW region. The tangles staining in tissue sections by the anti- PHF serum was abolished by its absorption with PHF polypeptides extracted from high and low molecular weight areas of SDS polyacrylamide gels but not with identically prepared neurofilament polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1983