Characterization of the AD7C-NTP cDNA expression in Alzheimer's disease and measurement of a 41-kD protein in cerebrospinal fluid.

We have isolated a novel Alu sequence-containing cDNA, designated AD7c-NTP, that is expressed in neurons, and overexpressed in brains with Alzheimer's disease (AD). The 1,442-nucleotide AD7c-NTP cDNA encodes an approximately 41-kD protein. Expression of AD7c-NTP was confirmed by nucleic acid sequencing of reverse transcriptase PCR products isolated from brain. AD7c-NTP cDNA probes hybridized with 1. 4 kB mRNA transcripts by Northern blot analysis, and monoclonal antibodies generated with the recombinant protein were immunoreactive with approximately 41-45-kD and approximately 18-21-kD molecules by Western blot analysis. In situ hybridization and immunostaining studies localized AD7c-NTP gene expression in neurons. Using a quantitative enzyme-linked sandwich immunoassay (Ghanbari, K., I. Beheshti, and H. Ghanbari, manuscript submitted for publication) constructed with antibodies to the recombinant protein, AD7c-NTP levels were measured under code in 323 clinical and postmortem cerebrospinal fluid (CSF) samples from AD, age-matched control, Parkinson's disease, and neurological disease control patients. The molecular mass of the AD7c-NTP detected in CSF was approximately 41 kD. In postmortem CSF, the mean concentration of AD7c-NTP in cases of definite AD (9.2+/-8.2 ng/ml) was higher than in the aged control group (1.6+/-0.9; P < 0.0001). In CSF samples from individuals with early possible or probable AD, the mean concentration of AD7c-NTP (4.6+/-3.4) was also elevated relative to the levels in CSF from age-matched (1.2+/-0.7) and neurological disease (1.0+/-0.9) controls, and ambulatory patients with Parkinson's disease (1.8+/-1.1) (all P < 0.001). CSF levels of AD7c-NTP were correlated with Blessed dementia scale scores (r = 0. 66; P = 0.0001) rather than age (r = -0.06; P > 0.1). In vitro studies demonstrated that overexpression of AD7c-NTP in transfected neuronal cells promotes neuritic sprouting and cell death, the two principal neuroanatomical lesions correlated with dementia in AD. The results suggest that abnormal AD7c-NTP expression is associated with AD neurodegeneration, and during the early stages of disease, CSF levels correlate with the severity of dementia.

Isolation and characterization of human antibodies targeting human aspartyl (asparaginyl) beta-hydroxylase.

Over-expression of the enzyme human aspartyl (asparaginyl) beta-hydroxylase (HAAH) has been detected in a variety of cancers. It is proposed that upon cellular transformation, HAAH is overexpressed and translocated to the tumor cell surface, rendering it a specific surface antigen for tumor cells. In this work, twelve human single-chain Fv fragments (scFv) against HAAH were isolated from a human non-immune scFv library displayed on the surface of yeast. Five of the twelve were reformatted as human IgG1. Two of the five IgGs, 6-22 and 6-23, showed significant binding to recombinant HAAH in ELISA, tumor cell lines, and tumor tissues. The apparent dissociation constants of 6-22 and 6-23 IgG were 1.0 +/- 0.2 nM and 20 +/- 10 nM respectively. These two antibodies were shown to target different domains of HAAH, with 6-22 targeting the catalytic domain of HAAH and 6-23 targeting the N-terminal non-catalytic domain of HAAH. 6-22 IgG was further characterized, as it had high affinity and targeted the catalytic domain. 6-22 IgG alone does not exhibit significant cytotoxicity toward the tumor cells. However, 6-22 internalizes into tumor cells and can therefore be employed to deliver cytotoxic moieties. A goat anti-human IgG-saporin conjugate was delivered into tumor cells by 6-22 IgG and hence elicited cytotoxicity toward the tumor cells in vitro. These tumor-binding human antibodies can potentially be used in both diagnosis and immunotherapy targeting HAAH-expressing tumor cells.

PAN-811 (3-aminopyridine-2-carboxaldehyde thiosemicarbazone), a novel neuroprotectant, elicits its function in primary neuronal cultures by up-regulating Bcl-2 expression.

Neurotoxicity in primary neurons was induced using hypoxia/hypoglycemia (H/H), veratridine (10microM), staurosporine (1microM) or glutamate (100microM), which resulted in 72%, 67%, 75% and 66% neuronal injury, respectively. 3-Aminopyridine-2-carboxaldehyde thiosemicarbazone (PAN-811; 10microM; Panacea Pharmaceuticals, Gaithersburg, MD) pretreatment for 24 h provided maximal neuroprotection of 89%, 42%, 47% and 89% against these toxicities, respectively. Glutamate or H/H treatment of cells increased cytosolic cytochrome c levels, which was blocked by pretreatment of cells with PAN-811. Pretreatment of neurons with PAN-811 produced a time-dependent increase in the protein level of Bcl-2, which was evident even after glutamate or H/H treatments. An up-regulation in the expression of the p53 and Bax genes was also observed following exposure to these neurotoxic insults; however, this increase was not suppressed by PAN-811 pretreatment. Functional inhibition of Bcl-2 by HA14-1 reduced the neuroprotective efficacy of PAN-811. PAN-811 treatment also abolished glutamate or H/H-mediated internucleosomal DNA fragmentation.

Protein alterations in olfactory neuroblasts from Alzheimer donors.

Definitive diagnosis of Alzheimer's disease (AD) is made by pathologic examination of postmortem brain tissue in conjunction with a clinical history of dementia. To date, there are no good biological markers for a positive diagnosis of AD in the living patient. In an effort to identify biological markers useful both in the clinical and pathologic diagnosis of AD, we have investigated disease-specific protein alterations in cultured olfactory neurons. Olfactory neurons are readily accessible by biopsy, can be propagated in primary cell culture as olfactory neuroblasts (ONs), and exhibit several elements of AD brain pathophysiology making them powerful tools for the study of AD. Two-dimensional gel analysis of ON proteins from neuropsychologically evaluated AD donors revealed a set of five proteins (Mr 17-50 kD, pI 4.8-6.7) that were significantly altered in concentration when compared to cells from age-matched controls. Further characterization and microsequence analysis could lead to the identification of proteins that may have important diagnostic or therapeutic value in the treatment of AD.

Neuronal CDK7 in hippocampus is related to aging and Alzheimer disease.

Despite their supposedly terminally-differentiated quiescent status, many neurons in Alzheimer disease display an ectopic re-expression of cell-cycle related proteins. In the highly regulated process of cell cycle, cyclin-dependent kinase 7 (Cdk7) plays a crucial role as a Cdk-activating kinase and activates all of the major Cdk-cyclin substrates. In this study, we demonstrate that Cdk7 immunoreactivity is significantly elevated in susceptible hippocampal neurons of Alzheimer disease patients in comparison with age-matched controls. Notably, the expression of Cdk7 is age-dependent, with decreased levels between the ages of 54 and 65 years and after the age of 78. While the Cdk7 levels in Alzheimer disease patients are higher than controls within each age group, the difference is greatest between ages 54-65 where disease susceptibility and/or progression is likely more related to genetic factors.

Neuronal polo-like kinase in Alzheimer disease indicates cell cycle changes.

Neurons of adults apparently lack the components necessary to complete the cell division process. Therefore, in Alzheimer disease, the increased expression of cell cycle-related proteins in degenerating neurons likely leads to an interrupted mitotic process associated with cytoskeletal abnormalities and, ultimately, neuronal degeneration. In this study, to further delineate the role of mitotic processes in the pathogenesis of Alzheimer disease, we undertook a study of polo-like kinase (Plk), a protein that plays a crucial role in the cell cycle. Our results show disease-related increases in Plk in susceptible hippocampal and cortical neurons in comparison to young or age-matched controls. An increase in neuronal Plk further implicates aberrations in cell cycle control in the pathogenesis of Alzheimer disease and provides a novel mechanistic basis for therapeutic intervention.

Immunochemical characterization of a monoclonal antibody specific for Alzheimer's disease associated protein.

In this study, the monoclonal antibody PHF-1 which recognizes epitopes unique to Alzheimer's disease associated proteins (ADAP) has been characterized. Crossed affinity immunoelectrophoresis was used to estimate the binding constant for the interaction of PHF-1 with ADAP and to estimate the fraction of PHF-1 reactive protein. The binding constant of PHF-1 was determined to be 1.3 x 10(-8) M. Furthermore, the effect of dephosphorylation on the electrophoretic pattern of the PHF-1 reactive protein and the ensuing changes in its immunoreactivity were demonstrated.

Detection of amyloid beta protein precursor immunoreactivity in normal and Alzheimer's disease cerebrospinal fluid.

The amyloid A4 (or beta protein), a 4.2 kD polypeptide, is a major component of amyloid deposits in the brains of patients with Alzheimer's Disease (AD). The self-aggregating amyloid A4 protein of AD is encoded as part of three larger proteins by the amyloid A4 precursor gene. The corresponding proteins have 695, 751 and 770 amino acid residues. To investigate the utility of amyloid beta protein precursor (A beta PP) as a diagnostic marker for AD an antiserum against a synthetic peptide (175-186), predicted from cDNA sequence for A beta PP, was used. The immunoreactivity of A beta PP in normal and AD cerebrospinal fluid (CSF) was measured by Western blot and detected with radiolabeled protein A. A total of fifty-seven CSF samples (AD = 27 and normal = 30) were analyzed for A beta PP immunoreactivity. A polyclonal antibody detected two major protein bands with apparent molecular weights of 105kD and 90kD both in normal and AD CSF. The difference between normal and AD CSF was not significant. These results indicate that immunoreactivity of A beta PP is present both in normal and AD CSF, and that the difference is too small to be used as a diagnostic marker.

A comparative study of myosin and its subunits in adult and neonatal-rat hearts and in rat heart cells from young and old cultures.

A possible explanation for the decrease in myosin Ca2+-dependent ATPase activity as rat heart cells age in culture is presented. The subunit structure and enzyme kinetics of myosin from adult and neonatal rat hearts and from rat heart cells of young and old cultures are compared. These studies indicate that the loss in Ca-ATPase activity of myosin from older cultures was an intrinsic property of the myosin itself. Myofibrillar fractions from the indicated four sources showed no qualitative or quantitative differences in electrophoretic patterns. Myosin from older cultures was more sensitive to alkaline denaturation than was myosin from younger cultures, as indicated by its more accelerated loss of K+(EDTA)-dependent ATPase activity after 10 min of incubation at pH 10. Furthermore, myosin from older cultures was more temperature-sensitive, as indicted by a more rapid loss of Ca-ATPase with decrease in assay temperature. It is suggested that there is either a change in conformation of myosin molecules at or near the active site of the enzyme or alternatively there is a change in light chain 1-light chain 2 and/or light-chain-heavy-chain interaction(s) in the myosin molecules under study.

A sandwich enzyme immunoassay for measuring AD7C-NTP as an Alzheimer's disease marker: AD7C test.

A simple, fast, reliable, and specific immunoassay has been developed to detect and measure AD7C-NTP, a biochemical marker for Alzheimer's disease, in cerebrospinal fluid (CSF). This assay, called the AD7C Test, is an enzyme-linked sandwich immunoassay (ELSIA) using 96 well microtiter plates. The plate surface is coated with a monoclonal antibody (N3I4) which has a high affinity and specificity for AD7C-NTP, capturing it effectively from CSF samples. The detection was achieved using a polyclonal antibody (ADRI). Both N3I4 and ADRI were generated using recombinantly produced AD7C-NTP. The assay is highly sensitive (30-50 pg), linear to 2.0 ng (r2 > 0.99), and reproducible (C.V. < 10%). The utility of the assay has been demonstrated using CSF specimens from early Alzheimer's disease patients and age matched controls (sensitivity of 89% and specificity of 89%).

A sandwich enzyme immunoassay for detecting and measuring Alzheimer's disease--associated proteins in human brain tissue.

A simple, fast, and reliable immunoassay has been developed to detect and measure Alzheimer's disease-associated proteins (ADAPs) in human brain tissue. This assay, called ALZ-EIA (brain), was developed for Abbott's quantum system, in which 1/4-in. beads are used as solid phase. The beads were coated with polyclonal IgG purified from sera obtained from rabbits immunized with a highly enriched Alzheimer's disease brain protein fraction for ADAP. The antigen (ADAP) is effectively captured by the polyclonal IgG coated on the beads. ALZ-50 (a mouse monoclonal IgM) is used as the detection antibody, and bound ALZ-50 is subsequently quantified by a horseradish peroxidase-linked goat antimouse IgM and appropriate substrate. The assay is linear up to 0.5 absorbance units (r = 0.9), reproducible (CV less than 10%), sensitive, and specific. With preformulated reagents and standard supplies, the assay is simple and rapid; 120 data points can readily be generated in about 4 hr.

Distribution of Alzheimer's disease-associated protein (ADAP) in 10 human brains.

ALZ50-based enzyme immunoassay was used to study distribution of Alzheimer's disease-associated protein (ADAP) in postmortem brain tissues of 5 Alzheimer's disease (AD) and 5 non-Alzheimer's disease (NAD) subjects. There are at least three AD-associated proteins, including A68. Levels are higher in brain regions with severe neuronal loss in AD: frontal, temporal, hippocampal cortex, and amygdala. No significant ADAP was found in the NAD samples (from 2 age-matched-1 clinically demented-and 3 younger subjects). ADAP levels in four regions of AD brains were not correlated to neuritic plaque count in corresponding regions of matching formaldehyde-fixed hemispheres.

Immunohistochemical and histopathologic correlates of Alzheimer's disease-associated Alz-50 immunoreactivity quantified in homogenates of cerebral tissue.

Alz-50 is a monoclonal antibody that immunoreacts with neurofibrillary tangles and neurites in brains with Alzheimer's disease (AD). In addition, the levels of Alz-50 immunoreactivity in brain, measured by either enzyme-linked immunosorbent assay or ALZ-enzyme-linked immunosorbant assay (EIA), are increased in AD relative to age-matched controls. The current study compares the distribution and extent of Alz-50 immunostaining with quantified levels of Alz-50 immunoreactivity measured in adjacent frozen blocks of tissue by ALZ-EIA. The brain tissue studied was obtained from individuals with AD, AD + Down's syndrome (AD + DN), Parkinson's disease with dementia (PD), or AD + PD, and from nondemented aged controls. In AD, AD + DN, and AD + PD, there were significantly higher densities of Alz-50-immunoreactive (AFI) neurons, more abundant diffuse AFI neurites, and higher ALZ-EIA values than in aged controls. In PD, the overall mean density of AFI neurons was significantly lower than in AD and AD + DN, but AFI neurites were as abundant as they were in brains with an AD diagnosis. However, PD was readily distinguished from AD and AD + DN by significantly lower mean ALZ-EIA values, and significantly lower densities of neurofilament-immuno-reactive AD lesions. Multiple-regression analysis demonstrated significant correlations between ALZ-EIA levels and the severity of AD lesions, and the density of AFI neurites, but not with the density of AFI neurons. Therefore, ALZ-EIA levels may represent only a portion of the Alz-50 immunoreactivity detectable by immunohistochemical staining.

Phosphorylated tau epitope of Alzheimer's disease is coupled to axon development in the avian central nervous system.

The monoclonal antibody PHF-1 recognizes phosphorylated tau isoforms present in paired helical filaments of Alzheimer's disease. We have found that PHF-1 immunoreactivity is present in chick brain, which expresses three major PHF-1-reactive proteins at the same molecular weights seen in humans. The developmental pattern of expression suggests a functional role in differentiation, rather than in programmed nerve cell death. Expression of PHF-1 immunoreactivity in developing retina was highly cell selective, showing robust staining of ganglion cells, the only long-axon neuron of the seven major retina cell types. The majority of ganglion cells were PHF-1 positive. The developmental window of expression extended at least from E6 through P0, well outside the period of embryonic ganglion cell death. Mature cells did not show PHF-1 immunoreactivity. In the embryo, staining was particularly robust in ganglion cell axons (optic fiber layer), and association of PHF-1 reactivity with axonal tracts also was seen in developing forebrain. PHF-1 polarization occurred at ages when staining with polyclonal anti-tau did not show axonal selectivity. Similarly, in cell cultures, PHF-1 immunoreactivity became localized to single neurites, but polyclonal anti-tau did not. These results indicate that, rather than being associated with cell degeneration, PHF-1 immunoreactivity in the developing nervous system is associated with early stages of axon formation, both in vivo and in vitro. Therefore, expression of PHF-1 immunoreactive proteins in Alzheimer's disease suggests that paired helical filament formation might be triggered by mechanisms related to axon regeneration.

Automated microparticle enzyme immunoassay for neural thread protein in cerebrospinal fluid from Alzheimer's disease patients.

An automated microparticle enzyme immunoassay (MEIA) with the IMx analyzer for the detection of neural thread protein (NTP) in cerebrospinal fluid (CSF) from Alzheimer's disease (AD) patients was developed. This assay uses monoclonal antibodies produced against the purified pancreatic form of the protein. The assay employs one monoclonal antibody covalently coupled to the microparticle to capture immunoreactive material in CSF or brain tissue. The second monoclonal antibody was conjugated to alkaline phosphatase and serves as detection antibody. The assay provides results in approximately 45 minutes with a sensitivity of 60 pg/ml (3 fmoles/ml). The titration curve of both normal and AD CSF resulted in a linear relationship with respect to the volume of CSF used. A similar relationship was observed when normal and AD brain tissue extracts were serially diluted. The molecular weight of NTP in CSF was approximately 20 kD as determined by gel filtration method under non-denaturing conditions. The recovery for pancreatic thread protein (PTP) spiked in either normal or AD CSF was 104% and 108%, respectively. Intra-, inter-, and total assay CVs (coefficient of variation) for controls were less than 2.9%, 3.3% and 3.0%, respectively. This assay will provide a useful tool in the study of the Alzheimer's disease and may help research in diagnosis and prognosis of Alzheimer's disease and related disorders.

Biochemical assay of Alzheimer's disease--associated protein(s) in human brain tissue. A clinical study.

The concentration of Alzheimer's disease-associated protein (ADAP) was measured in postmortem brain tissue samples of temporal or frontal cortex from 111 human brains using a sandwich immunoassay. Alzheimer's disease-associated protein has three major ALZ-50-reactive subunits, including A-68. This assay utilizes ALZ-50 and a rabbit antibody raised against a highly ADAP-enriched brain protein fraction. The frequently observed cross-reactivity of ALZ-50 with normal brain components in direct immunoassays is minimized by this configuration. There were 27 normal controls, 28 neurologic disease controls, and 56 Alzheimer's disease cases. The normal control and neurologic disease control cases had essentially no detectable level of ADAP, while ADAP was clearly detected in 85.7% of the Alzheimer's disease cases. Clinical dementia, neuritic plaques, and old age per se are not correlated with increased ADAP levels. This biochemical assay of ADAP may prove to be helpful as an adjunct in the clinicopathologic diagnosis of Alzheimer's disease.

Haloperidol induced CSF protein variations in schizophrenic patients: as studied by two-dimensional electrophoresis.

High resolution two-dimensional electrophoresis of cerebrospinal fluid (CSF) from 10 schizophrenic patients demonstrated a 21% average difference in the number of proteins which could be detected in patients undergoing haloperidol therapy when compared with CSF from the same patients after withdrawal from neuroleptic treatment. Proteins affected were trace proteins, as we found no significant variation in either the total CSF protein content or the integrated protein density on each electrophoretic gel. Three mechanisms which might account for these observations are: (1) a small change in liver protein synthesis or degradation would have little if any visible effect on the concentration of major blood or CSF proteins, such as albumin, but it could significantly alter trace proteins, such as alpha 2-haptoglobin, since their concentrations are orders of magnitude less than that of the major proteins, (2) haloperidol might alter the blood-CSF protein filtration system which could affect the visibility of the trace proteins, and (3) proteins synthesized in the Central Nervous System (CNS) or enhanced in the CSF could be differentially affected by haloperidol. While additional research will be required to determine the basis for the effects of haloperidol on CSF proteins, the current studies provide information which may be helpful in delineating disease specific protein alterations from those induced by drug therapy.

Cerebrospinal fluid protein variations in common to Alzheimer's disease and schizophrenia.

Analysis of silver stained two-dimensional (2D) gels of cerebrospinal fluid (CSF) from 27 patients with schizophrenia (SCZ) and 10 patients with Alzheimer's disease (AD) revealed an increase in the relative amount of a polypeptide of 18,000M(r) and isoelectric point of 6.5 when compared to the appropriate controls. This protein was identified by its electrophoretic characteristics and by immune analysis of Western blots as an isoform of alpha-2 haptoglobin, provisionally identified as alpha-2FS haptoglobin. Alzheimer's disease versus control CSF samples showed a 6.8-fold increase in the percent mean density value of this haptoglobin isoform (n = 10 AD vs 11 control; P > 0.025) while a 4.4-fold increase was observed in the schizophrenic patients (n = 17 SCZ vs 10 control; P > 0.001). Two additional polypeptides (proteins '127' and '128') of 40,000 M(r) and isoelectric points 5.7 and 5.9, respectively, described previously by this laboratory, were found in the CSF of 27% of schizophrenics, 23% of the Alzheimer's disease patients, and 4% of the controls in the current study. The presence of proteins 127 and 128, as well as the increased concentrations of alpha-2 haptoglobin in the CSF of Alzheimer's disease and schizophrenic patients, may be useful as diagnostic biological markers. They may also indicate a common pathophysiology between these diseases.