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Biomedical subjects

L A Hansen

Publications and source records attributed to L A Hansen.

At least 37 records · Page 2Linked to original sources
PubMed2000

The decline in synapses and cholinergic activity is asynchronous in Alzheimer's disease.

OBJECTIVE: To determine the timing of cholinergic loss and reduction of synapses in AD. BACKGROUND: Decrements in neocortical synapses and cholinergic function occur in AD and correlate with cognitive decline. However, how early in the disease process these changes appear remains unclear. METHODS: An autopsy series of 89 demented patients with pathologically confirmed AD (National Institute on Aging and Consortium to Establish a Registry for Alzheimer's Disease criteria) and 18 normal control subjects (NC). The AD cases were stratified according to their last Mini-Mental State Examination (MMSE) score prior to death as mild (MMSE = 20; n = 14), moderate (MMSE = 10 to 19; n = 20), severe (MMSE = 1 to 9; n = 29), and very severe (MMSE = 0; n = 26). Midfrontal (MF) synapse density was assessed by dot-immunobinding assay for synaptophysin (Syn), and MF choline acetyltransferase (ChAT) activity was determined using standard protocols. RESULTS: Compared with those in NC, neither Syn nor ChAT was appreciably reduced in patients with mild AD at death. Decline of ChAT was significant only in AD patients who died in the late stages of the disease and was maximal in those who had more severely deteriorated. In contrast, decline of Syn was significant and almost maximal in patients in intermediate or moderate stages. Consequently, the last MMSE score prior to death correlated more strongly with ChAT than Syn when the AD cohort included more impaired patients (r = 0.46 versus 0.40). The reverse occurred when only less impaired patients (MMSE = 10) were included in the analyses (r = 0.28 versus 0.64). There was only a modest correlation between Syn and ChAT activity. CONCLUSIONS: The results imply an asynchronous pattern of decline of synapses and cholinergic activity, with Syn loss preceding ChAT decrements. However, neither MF synapse reduction nor cholinergic dysfunction appears to be an early event in AD.

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PubMed2000

The epidermal growth factor receptor is required to maintain the proliferative population in the basal compartment of epidermal tumors.

Previous studies using keratinocytes from epidermal growth factor receptor (EGFR)-deficient mice revealed that the EGFR is not required for papilloma formation initiated by a mutant rasHa gene, although the tumors that develop are very small (A. A. Dlugosz et aL, Cancer Res., 57: 3180-3188, 1997). The current study used a combination of bromodeoxyuridine pulse-chase, proliferating cell nuclear antigen distribution, and differentiation marker analysis to reveal the following: (a) the EGFR was required to maintain the proliferative population in the basal cell compartment of papillomas; (b) in the absence of EGFR, cycling tumor cells migrated into the suprabasal compartment and initiated the differentiation program prematurely; and (c) these changes were associated with cell cycle arrest. Further analysis of v-rasHa-transformed EGFR-deficient keratinocytes in vitro indicated that such cells migrated more on and attached less to extracellular matrix components. Together, these studies reveal that an essential function for the EGFR pathway in squamous tumors is to maintain a proliferative pool of basal cells and prevent premature terminal differentiation.

Animals↗
PubMed2000

E4 allele dosage does not predict cholinergic activity or synapse loss in Alzheimer's disease.

OBJECTIVE: To investigate the relationship between apolipoprotein E (APOE) genotype and both cholinergic dysfunction and synapse loss in AD. BACKGROUND: A reduction in neocortical synapses and marked losses in the cholinergic system occur in AD. It has been suggested that the number of APOE epsilon4 alleles is inversely related to choline acetyltransferase (ChAT) activity, thereby influencing cholinergic function. Whether APOE genotype may influence neocortical synapse loss remains unclear. METHODS: An autopsy series of 182 patients with AD (National Institute on Aging and Consortium to Establish a Registry for Alzheimer's Disease criteria) and 16 normal controls (NC). APOE genotype was determined in blood samples or in postmortem brain tissue. Midfrontal synapse counts (AU/microg) were quantified by a dot-immunobinding assay for synaptophysin (Syn). Midfrontal ChAT activity (nmol/h/100 mg) was assessed using standard assays. RESULTS: Mean midfrontal ChAT activity and Syn were both significantly reduced in patients with AD compared with NC. The relationship between ChAT activity and number of epsilon4 allele copies in AD was complex, with ChAT activity lower in patients with either two or no epsilon4 alleles compared with those with one epsilon4 allele. There was no relationship between APOE genotype and synapse loss in AD. Syn density was almost identical across the three genotypes. CONCLUSIONS: Unlike other studies, we failed to detect a linear relationship between ChAT activity and number of epsilon4 allele copies in the midfrontal cortex of this large sample of patients with AD. Our data also show that the presence of epsilon4 allele does not influence midfrontal synapse loss in AD. This suggests that factors other than APOE genotype may be operative in the decline in midfrontal cholinergic function and synapses seen in AD.

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PubMed2000

Cholinergic dysfunction in diseases with Lewy bodies.

OBJECTIVE: To evaluate cholinergic activity in diseases with Lewy bodies (LB; LB variant of AD [LBV], diffuse LB disease [DLBD], and Parkinson's disease [PD]) to determine if 1) AD changes are requisite to cholinergic dysfunction, 2) cholinergic activity declines to the same extent in neocortical and archicortical areas, and 3) cholinergic loss is influenced by APOE genotype. BACKGROUND: Like AD, diseases with LB are associated with decreased choline acetyltransferase (ChAT) activity. Increased APOE epsilon4 allele frequency has been reported in LBV. Whether APOE genotype affects cholinergic function in LBV remains unclear. METHODS: An autopsy series of 182 AD (National Institute on Aging and Consortium to Establish a Registry for Alzheimer's Disease criteria), 49 LBV, 11 PD, 6 DLBD, and 16 normal control (NC) subjects. APOE genotype and ChAT activity (nmol/h/100 mg) in the midfrontal and hippocampal cortices were determined. RESULTS: Mean midfrontal ChAT activity was markedly reduced in diseases with LB (LBV: 53.3 +/- 39.0; PD: 54.8 +/- 35.7; DLBD: 41.3 +/- 24.8) compared to NC (255.4 +/- 134.6; p < 0.001) and AD (122.6 +/- 78.9; p < 0.05). Among diseases with LB, midfrontal ChAT activity was decreased to a similar extent in patients with (LBV) and without (DLBD and PD) AD pathology. Although mean ChAT activity for LBV was less than half that for AD in the midfrontal cortex, it was similar to that for AD in the hippocampus (LBV: 243.5 +/- 189.7; AD: 322.8 +/- 265.6; p > 0.05). However, hippocampal ChAT activity for both AD and LBV was lower than that for NC (666.5 +/- 360.3; p < 0.001). The epsilon4 allele dosage did not influence midfrontal ChAT activity in LBV. CONCLUSION: Marked losses in midfrontal ChAT activity occur in diseases with LB, independent of coexistent AD changes. A greater midfrontal, as opposed to hippocampal, cholinergic deficit may differentiate LBV from AD. The lack of a relationship between epsilon4 allele dosage and midfrontal ChAT activity suggests that other factors may play a role in its decline in LBV.

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PubMed2000

Changes in pathological findings at autopsy in AIDS cases for the last 15 years.

OBJECTIVE: To analyze changes in frequency of systemic AIDS pathology over time and its relationship to central nervous system pathology. DESIGN AND METHODS: A total of 390 AIDS autopsy cases obtained at University of California at San Diego Medical Center from 1982 to 1998 were reviewed retrospectively and linear regression analysis was used to evaluate significance of changes over time. RESULTS: Overall, the frequency of cytomegalovirus, Pneumocystis carinii pneumonia and Mycobacterium avium complex decreased, whereas bacterial infections increased and the frequency of fungal infection remained unchanged over time. The frequency of non-Hodgkin's lymphoma showed an upward trend over time, while the frequency of Kaposi's sarcoma remained unchanged. Following involvement of the lung (84%), the brain continued to be the second most frequently affected organ (63%). Whereas alterations of the brain by opportunistic infections or non-Hodgkin's lymphoma showed a downward trend, HIV encephalitis continued to be detected in at least 25% of the cases. Cases with advanced HIV-related neuropathology and cases with no HIV involvement of the brain showed significant systemic pathology with opportunistic infections and neoplasms. In contrast, cases with early brain pathology (e.g., lymphocytic meningitis) showed minimal systemic pathology. Overall these trends remained unchanged throughout the total period covered by this study. CONCLUSIONS: This study suggests that despite the beneficial effects of antiretroviral and anti-opportunistic infection therapy, involvement of the brain by HIV continues to be a frequent autopsy finding.

AIDS-Related Opportunistic Infections↗
PubMed2000

Small concomitant vascular lesions do not influence rates of cognitive decline in patients with Alzheimer disease.

OBJECTIVE: To determine the relation between concomitant small cerebral infarction and clinical progression of Alzheimer disease (AD). DESIGN: A retrospective clinicopathologic study of patients with AD. METHODS: We searched the databases of the University of California, San Diego, Alzheimer's Disease Research Center, La Jolla, for patients with an autopsy diagnosis of definite AD with or without a concomitant small cerebral infarction. Clinical and neuropsychologic data obtained during longitudinal follow-up were available for 201 subjects with AD neuropathologic features and 36 with AD and concomitant cerebral infarcts (volume, < 10 cm(3)). The rates of cognitive decline on the Mini-Mental State Examination and the Dementia Rating Scale were each calculated and compared between the 2 groups. RESULTS: The age at death was significantly (P = .05) higher and the Braak stage was lower in patients with mixed AD and infarct pathological features compared with those with AD pathological features only. The rate of cognitive decline over time was not significantly (P > or = .20 for all) different between the 2 groups. There was a trend for the presence of a cerebral infarct to be associated with more severe clinical dementia (P =.08) as measured by the Dementia Rating Scale, but no such trend for the Mini-Mental State Examination. CONCLUSION: This clinicopathologic correlation study suggests that concomitant small cerebral infarcts with a total volume of less than 10 cm(3) do not significantly influence the overall rate of global cognitive decline in patients with AD. Arch Neurol. 2000;57:1474-1479

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PubMed2000

Diagnostic accuracy of dementia with Lewy bodies.

BACKGROUND: Diagnostic criteria for dementia with Lewy bodies (DLB) are still evolving. No data exist on prospective differentiation of DLB and Alzheimer disease (AD). OBJECTIVE: To examine the clinician's diagnostic accuracy for DLB and analyze factors contributing to false-positive DLB diagnoses. METHODS: A prospective series of 10 patients with clinically diagnosed DLB who came to autopsy was compared with 32 autopsy-confirmed cases of DLB (27 Lewy body variant, 5 diffuse Lewy body disease) and 20 autopsy-confirmed cases of AD (matched on age, sex, education, and initial Mini-Mental State Examination score) with regard to distinguishing and/or confounding clinical features. RESULTS: The clinical diagnostic accuracy for DLB was 50%, with 5 of the 10 patients clinically presumed to have DLB confirmed at autopsy. Of the 5 misdiagnosed cases, 4 had AD and 1 had progressive supranuclear palsy. The misdiagnosed DLB cases who had pure AD had fewer hallucinations (25%) than those with Lewy body variant (63%) or diffuse Lewy body disease (100%) (P = .048); however, an equal amount of spontaneous (in the absence of neuroleptics) extrapyramidal signs was found. There were no differences among groups with regard to daily fluctuations in cognition or falls. Compared with the AD control group, the misdiagnosed DLB cases with pure AD showed significantly more spontaneous extrapyramidal signs (P< or =.02). CONCLUSIONS: The clinician's diagnostic accuracy for DLB was poor. Early spontaneous extrapyramidal signs in AD were associated with false-positive clinical diagnoses of DLB. The distinction between DLB and AD may be improved by greater emphasis on hallucinations.

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PubMed2000

Association between severe cerebral amyloid angiopathy and cerebrovascular lesions in Alzheimer disease is not a spurious one attributable to apolipoprotein E4.

BACKGROUND: We have previously reported an association between severe cerebral amyloid angiopathy (CAA) and cerebrovascular lesions in Alzheimer disease (AD), which is particularly strong for microinfarcts, hemorrhages, and multiple lesion types. Cerebral amyloid angiopathy has also been associated with the apolipoprotein E4 (APOE4) genotype, which is in turn associated with premature coronary artery disease and atherosclerosis. OBJECTIVE: To test whether severe CAA would be more strongly associated with cerebrovascular lesions than would APOE4 genotype. METHODS: We reviewed 306 cases of autopsy-confirmed AD (from the University of California, San Diego, brain autopsy series) to assess whether APOE genotype and other clinical risk factors were predictive of vascular lesions (VLs) in AD. Cerebral amyloid angiopathy severity was assessed using a semiquantitative scale in 4 brain regions (ie, hippocampus, midfrontal cortex, inferior parietal cortex, and superior temporal cortex) and an average score was computed for each case. RESULTS: We found that severe CAA was associated with an increased frequency of VLs (33% of the cases of severe CAA had VLs vs 19% of the cases of mild or absent CAA; P=.02). While the APOE4/4 genotype was associated with an increased severity of CAA, there was no significant relationship between APOE genotype and frequency of VLs. Logistic regression models showed that severe CAA, advanced age, atherosclerosis, and Hachinski Ischemia Scale score of 7 or more were all significantly associated with VLs, but the number of APOE4 alleles, history of hypertension, coronary artery disease, sex, and serum cholesterol levels had nonsignificant effects. Within strata of APOE genotype, the presence of severe CAA was associated with increased frequency of VLs (eg, within APOE4/4 homozygotes, VLs were present within 47% of the cases of severe CAA vs 9.5% of the cases of mild or absent CAA; P=.01). CONCLUSIONS: Severe CAA confers a greater risk of VLs in AD, even within strata of APOE genotype. Therefore, the association between severe CAA and VLs in AD is not a spurious one owing to APOE4. Overall, our cases of AD with APOE4 do not seem to be a more "vasculopathic" subtype of AD. The mechanisms by which CAA produces VLs of various types need to be further elucidated, as these are probably important in producing the common entity of "mixed" AD/vascular dementia. Arch Neurol. 2000.

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PubMed2000

Relationship between severe amyloid angiopathy, apolipoprotein E genotype, and vascular lesions in Alzheimer's disease.

In this brief review, we aim to describe the complex relationship between cerebral amyloid angiopathy (CAA), apolipoprotein E (ApoE), and cerebrovascular lesions in Alzheimer's disease (AD). First, we review the evidence that CAA is associated with, and may cause, specific types of vascular lesions (VLs). In addition to being a leading cause of lobar hemorrhages in the elderly, CAA has been implicated as a likely cause of small infarcts, microinfarcts, and incomplete infarctions in the deep white matter. We also review the role that ApoE4 (the major genetic risk factor for AD) has in predisposing toward CAA, coronary artery disease, and possibly toward cerebrovascular disease. Last, we provide evidence that the association between CAA and VLs is not a spurious one due to an increase in the ApoE4 genotype. Even within patient groups with the same ApoE genotype (specifically, E4/4 homozygotes and E3/3 homozygotes), our recent analyses have found significant increases in VLs in association with severe CAA. We discuss the implications of this finding as advancing a pathogenic role for severe CAA in producing many of the VLs commonly found in AD cases.

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PubMed2000

Distribution of obstructive intimal lesions and their cellular phenotypes in chronic pulmonary hypertension. A morphometric and immunohistochemical study.

We investigated the distribution of pulmonary arteriopathy in chronic pulmonary hypertension (PH) in a quantitative histopathologic study, using computer-assisted image analysis. We also examined the histologic manifestations and cellular phenotypes of various obstructive intimal lesions in PH with an immunohistochemical method. A total of 53 lungs removed at autopsy or explantation were obtained for the study from 51 documented cases of moderate to severe PH (15 cases of primary pulmonary hypertension [PPH], eight cases of Eisenmenger's syndrome [EISEN], 22 cases of chronic major-vessel thromboembolic disease [CTED], and three cases of PH associated with other known causes), and two unused donor lungs served as normal controls. Intimal thickening in PPH was most prominent in small pulmonary arteries and arterioles less than 200 micrometer in diameter. Plexiform lesions in PPH were associated with significantly smaller arteries than in EISEN. Arteries larger than 400 micrometer showed a significant intimal thickening only in CTED. Obstructive intimal lesions in PH comprised a morphologic spectrum with frequent intermediate forms between plexiform and thrombotic lesions. Most cells within various intimal lesions showed an immunoprofile of myofibroblasts that were positive for vimentin and alpha-smooth muscle actin, but negative for desmin and endothelial markers including Factor VIII, clonal designator (CD)31, and CD34. Endothelial markers were positive only in the single layer of cells lining slitlike lumens, when the latter were present. In conclusion, major types of PH had characteristic distribution patterns of obstructive intimal lesions, showing mainly a myofibroblastic phenotype and variable endothelial/vascular differentiation.

Adult↗
PubMed2000

Retinoids in chemoprevention and differentiation therapy.

Retinoids are essential for the maintenance of epithelial differentiation. As such, they play a fundamental role in chemoprevention of epithelial carcinogenesis and in differentiation therapy. Physiological retinoic acid is obtained through two oxidation steps from dietary retinol, i.e. retinol-->retinal-->retinoic acid. The latter retinal-->retinoic acid step is irreversible and eventually marks disposal of this essential nutrient, through cytochrome P450-dependent oxidative steps. Mutant mice deficient in aryl hydrocarbon receptor (AHR) accumulate retinyl palmitate, retinol and retinoic acid. This suggests a direct connection between the AHR and retinoid homeostasis. Retinoids control gene expression through the nuclear retinoic acid receptors (RARs) alpha, beta and gamma and 9-cis-retinoic acid receptors alpha, beta and gamma, which bind with high affinity the natural ligands all-trans-retinoic acid and 9-cis-retinoic acid, respectively. Retinoids are effective chemopreventive agents against skin, head and neck, breast, liver and other forms of cancer. Differentiation therapy of acute promyelocytic leukemia (APL) is based on the ability of retinoic acid to induce differentiation of leukemic promyelocytes. Patients with relapsed, retinoid-resistant APL are now being treated with arsenic oxide, which results in apoptosis of the leukemic cells. Interestingly, induction of differentiation in promyelocytes and consequent remission of APL following retinoid therapy depends on expression of a chimeric PML-RAR alpha fusion protein resulting from a t(15;17) chromosomal translocation. This protein functions as a dominant negative against the function of both PML and RARs and its overexpression is able to recreate the phenotypes of the disease in transgenic mice. The development of new, more effective and less toxic retinoids, alone or in combination with other drugs, may provide additional avenues for cancer chemoprevention and differentiation therapy.

Animals↗
PubMed1999

Alternative splicing patterns of CYP2D genes in human brain and neurodegenerative disorders.

The expression patterns of alternatively spliced forms of the CYP2D (6, 7, 7A, 7B) gene were analyzed in the brains of individuals with Lewy body disease (LBD) and correlated with CYP2D6 polymorphisms. Five different alternatively spliced transcripts were identified. The most common was the deletion of exon 6 (87.3% of cases), followed by a 91-base pair fragment deletion at the 3' end of the gene (63.9% of cases). There was no correlation between the polymorphisms in the CYP2D6B gene or presence of LBD and these five alternatively spliced transcripts. Susceptibility to LBD may occur through mechanisms other than altered mRNA splicing of the CYP2D6 gene.

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PubMed1999

Endotoxin potency in the A549 lung epithelial cell bioassay and the limulus amebocyte lysate assay.

The purpose of this study was to elucidate to what extent the potency of endotoxins measured by the limulus amebocyte lysate (LAL) assay is reflected in the potency in an in vitro assay based on release of interleukin-8 (IL-8) from a lung epithelial cell line, A549. Lipopolysaccharides (LPS) from Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enteritidis and detoxified LPS from E. coli were applied in serial dilutions in the LAL assay and in the A549 bioassay. Also 19 organic dust samples from waste recycling plants were tested. The A549 cells were incubated for 24 h with LPS or dust, and the IL-8 secretion was determined by ELISA. The method for evaluation of the LAL assay showed linearity for the four endotoxins. Using the slope as a measure of the potency factor (PF), LPS from E. coli and S. enteritidis was about four times more potent than that for LPS from K. pneumoniae and P. aeruginosa. In the A549 bioassay each of the different types of endotoxin had characteristic and very different dose-response curves. The potency of the LPS, in the A549 bioassay, ranked as follows K. pneumoniae > P. aeruginosa > E. coli > or = S. enteritidis. The content of endotoxin in the dust samples did not correlate with their potency in the A549 bioassay. The present study indicates a poor correlation between the potency of endotoxin in the LAL assay compared with the A549 bioassay. The lack of correlation when organic dust samples are tested may reflect the fact that these samples contain biological active compounds, which are non-reactive in the LAL-assay but stimulate IL-8 secretion from epithelial cells.

Animals↗
PubMed1999

Case of the month: March 1999--A 26 year old HIV positive male with dura based masses.

A 26-year-old male with AIDS presented with a chief complaint of headaches and neck pain. An MRI revealed two enhancing extra-axial dura based masses, one in the area of the left sphenoid wing and one at the level of C2-3. In both cases, microscopic sections showed actin positive spindle cell neoplasms with long slender nuclei, consistent with leiomyomas. Both tumors were positive for Epstein Barr virus by in situ hybridization. This case report serves to emphasize the importance of considering soft tissue tumors such as leiomyoma in the differential diagnosis of mass lesions that occur in the central nervous system in AIDS and discusses the role of EBV in tumorigenesis.

Acquired Immunodeficiency Syndrome↗
PubMed1999

The role of Na+-H+ exchange in fluid and solute transport in the rat efferent ducts.

In vivo microperfusion techniques were used to investigate the role of Na+-H+ exchange in the efferent ducts of the rat. Individual efferent ducts were perfused with a Krebs-Ringer bicarbonate solution (KRB) containing 0, 1, 3, 5 or 7.5 mM amiloride. Concentrations of 1-5 mM amiloride inhibited fluid reabsorption from the efferent ducts in a linear dose-dependent manner with an apparent Km of 3 mM. Inhibition was maximal at 5 mM with reabsorption reduced by about 70 %. The effects of amiloride were completely reversible and there was little effect of amiloride on luminal osmolality and concentrations of Na+, Cl- or K+. It is concluded that Na+-H+ exchange is one of the principal mechanisms responsible for fluid and electrolyte reabsorption in the efferent ducts and offers a means by which the efferent ducts are able to achieve flow-dependent, autoregulated fluid reabsorption.

Amiloride↗
PubMed1998

Characterization of Wnt gene expression in murine skin: possible involvement of epidermis-derived Wnt-4 in cutaneous epithelial-mesenchymal interactions.

Wnt glycoproteins mediate short range intracellular communication that facilitates morphogenesis and, in some settings, promotes tumor formation. Although the involvement of the Drosophila homolog wingless in ectodermal patterning is well established, the role that Wnt genes play in mammalian skin biology is not defined. We detected Wnt-4 and Wnt-10b mRNA in adult murine epidermis using degenerate primers and reverse transcriptase PCR, and confirmed expression by RNase protection. Normal murine keratinocytes and a melanocyte cell line (melan-A) propagated in vitro also contained Wnt-4 mRNA, whereas dermal fibroblasts and Langerhans cell-like dendritic cells did not. Because Wnt-4 mRNA was more abundant than Wnt-10b mRNA in epidermis and Wnt-10b trancripts were not detected in cells propagated in vitro, additional studies emphasized Wnt-4 exclusively. Wnt-4 mRNA levels were increased in cultured keratinocytes as they approached confluence and were strikingly downregulated by mitogenic growth factors. Although Wnt-4 mRNA levels were not modulated during calcium-induced keratinocyte differentiation in vitro, assessment of Wnt-4 transcripts in keratinocyte cell lines suggested that loss of Wnt-4 gene expression was associated with a less differentiated, more malignant, phenotype. Despite this, epidermal abnormalities were not identified in newborn Wnt-4 null (-/-) skin, or in full-thickness -/- skin that was engrafted to nude or athymic mice and allowed to mature for as long as 3 months. However, histologic examination of newborn Wnt-4 null skin did reveal fibroplasia involving the dermis with increased accumulation of type I collagen fibrils. These results indicate that several Wnt genes are expressed in adult murine epidermis and suggest that Wnt-4 proteins may be involved in epidermal-dermal interactions in mammalian skin.

Animals↗
PubMed1998

Increased levels of alpha-1-antichymotrypsin in brains of patients with Alzheimer's disease correlate with activated astrocytes and are affected by APOE 4 genotype.

Levels of alpha-1-antichymotrypsin (ACT) were higher in brain homogenates of patients with Alzheimer's disease (AD) than controls. Brain tissues from the same patients and controls were immunostained with antibodies specific for microglia or astrocytes, the leukocyte common antigen (CD45) and glial fibrillary acidic protein (GFAP), respectively. Both activated CD45 and GFAP cells were increased in AD. Astroglia were divided into scattered (CD45sc) and clustered microglia (CD45cl) or scattered (GFAPsc) and clustered astrocytes (GFAPcl). Clustered cells were defined according their tendency to form focal aggregates. CD45cl and GFAPcl cells were present only in AD brain, while CD45sc and GFAPsc positive cells were present either in AD or control brains, with AD brains showing increased numbers of both cell types. A positive correlation between brain ACT levels and the number of GFAPsc positive cells was present in AD. AD patients with APOE 4 allele showed increased levels of ACT and increased CD45sc positive cells. Elevated ACT levels in the brain of AD patients could be interpreted as a metabolic response of astrocytes which might modulate the potentially deleterious activation of microglia cells.

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