Peripheral markers of oxidative stress in probable Alzheimer patients.

BACKGROUND: The current research on Alzheimer's disease is mainly focused in the post-mortem characterization of pathological and biochemical alterations in the brain. The finding of peripheral markers that could be associated with the changes observed in the Alzheimer's brain would be of interest in this field. The aim of the present study was to evaluate the state of different peripheral markers of oxidative stress in probable Alzheimer patients and compare them with a group of healthy individuals. DESIGN: The determinations made include the plasma total antioxidant capacity (TRAP) and tert-butyl hydroperoxide-initiated chemiluminescence and catalase activity in erythrocytes from 18 patients with probable Alzheimer's disease and 18 matched control subjects with normal cognitive function. RESULTS: TRAP was decreased in Alzheimer patients by 24% (control group 308 micromol L-1 Trolox, SEM 34, n = 18). tert-Butyl hydroperoxide-initiated chemiluminescence and catalase activity showed an increase in erythrocytes from Alzheimer patients by 52% (control group 116 700 cps mg-1 haemoglobin, SEM 6690) and 75% (control group 2.55 pmol mg-1 protein, SEM 0.39, n = 18) respectively. CONCLUSION: Oxidative stress in the blood of probable Alzheimer patients could be a reflection of the brain condition and suggests that oxygen free radicals could be partially responsible of the damage observed in this disease.

The antioxidant enzymatic blood profile in Alzheimer's and vascular diseases. Their association and a possible assay to differentiate demented subjects and controls.

A study of several elements of the antioxidative system: Cu-Zn superoxide dismutase (SOD), catalase (CAT), glutathione system (GLU), chemiluminescence (CHE), and antioxidant capacity (AOX), was conducted in 20 demented probable Alzheimer's (DAT), and 15 vascular demented (VD) patients, 19 control (C) subjects, and 11 relatives (F) of one DAT patient. A significant association was found between the variables of the antioxidant system, measured in blood samples, and the neurological pathologies VD and DAT: Kruskal-Wallis test; p = 0.0006 (p = 0.014 when the analysis did not include SOD). This demonstrated that VD and DAT diseases are accompanied by oxidative disorders. The VD and DAT diseases are differentially distinguishable by changes in blood profiles. A graphical method for classification, the Principal Components Analysis (PCA), distinguished between demented and non-demented subjects on the basis of their laboratory variables. A numerical method, Discriminant Functions (DF), constructed to separate the clinical groups on the basis of the same variables, obtained relatively high percentages of success: 92% of demented were detected against healthy subjects; of the latter 82% have been correctly identified as non-demented. Discrimination between VD and DAT patients was achieved for 100% of VD and 86% of DAT patients. DF were similarly successful in detecting the healthy condition of DAT relatives. Possible different mechanisms involved in H2O2 elimination in DAT and VD patients are proposed, where CAT is the responsible enzyme of this reaction in DAT patients, while in VD this function would be achieved mainly through the action of GLU. It seems that SOD levels are stable, at least, within one year. Variations appear to be linked with clinical changes.

Treatment strategies for early-stage chronic lymphocytic leukemia: can interferon-inducible MxA protein and tumor necrosis factor play a role as predictive markers for response to interferon therapy?

The potential benefit of interferon (IFN)-alpha therapy in early-stage B cell chronic lymphocytic leukemia (B-CLL) patients is still under discussion, and no assays are available to distinguish potential responders from nonresponders. Herein we analyzed the usefulness of serum tumor necrosis factor (TNF, a cytokine released by CLL cells) and MxA protein (an intracellular marker for biologic activity of endogenous IFN) concentrations as predictive measurements for evolution and response to IFN therapy in early-stage CLL patients. TNF levels and MxA expression were determined at diagnosis in 21 CLL patients. A statistically significant correlation was found between low TNF levels and MxA expression and between high TNF levels and no measurable MxA expression. The patients were then randomized to receive IFN-alpha or no therapy and were evaluated for response and evolution. When response to IFN-alpha therapy was considered, it became apparent that early-stage CLL patients with higher TNF levels and no measurable MxA expression were more likely to benefit from IFN therapy, whereas those patients with lower TNF levels and MxA expression could be considered CLL candidates for longer survival without therapy. More patients have to be tested to strengthen the value of MxA expression and TNF concentrations for subsequent response to IFN-alpha therapy.

Excessive urokinase-type plasminogen activator activity in the euglobulin fraction of patients with Alzheimer-type dementia.

We examined the activity of the serine protease urokinase-type plasminogen activator (uPA) present in the euglobulin fraction of plasma from 17 demented patients with probable Alzheimer's disease (AD), 12 patients with vascular dementia (VD) and 10 healthy controls. Euglobulin protein fractions were separated by electrophoresis and gels were incubated at the surface of plasminogen-rich casein-agarose underlays. The degradative activity of uPA in this system was measured by densitometric analysis. In 8/17 (47%) patients with AD we observed an excessive uPA activity (> 200 mIU/ml). In contrast, only 2/12 (16%) patients with VD and 1/10 (10%) control subjects revealed a comparable increase in circulating uPA activity. Further evaluation of dementia stage in patients with AD allow us to associate high levels of uPA activity with severity of disease. uPA levels were significantly elevated (2.8-fold increase) in AD patients with severe cognitive and memory impairments (Alzheimer Disease Assessment Scale) with respect to controls, VD patients or AD patients with moderate cognitive and memory impairments (P < 0.001, ANOVA). Our data suggest that the anormalities in circulating fibrinolytic enzymes could be correlated with the severity of dementia. In light of this findings, the free uPA activity in euglobulin plasma fraction should be considered a marker of serious damage in patients with AD.

Peripheral markers and diagnostic criteria in Alzheimer's disease: critical evaluations.

This review analyzes recent developments in diagnostic criteria and peripheral markers used clinically in the definitive diagnosis of Alzheimer's disease (AD), comparing past and current views, together with a discussion of their shortcoming and difficulties of implementation. Consideration is given to studies on the presence of amyloid substances outside the central nervous system: in cerebrospinal fluid, in plasma, in primary cultures, and in continuous cultures of cell lines of neuronal and glial origin. We discuss alterations of cholinesterases and noradrenaline in red blood cells (RBC) in AD and, with relation to the infectious theory, the presence of spirochaetes in patients. The activities of the enzymes leading to the formation of amyloid substances and those reflecting more general alterations of metabolic processes are considered, both in respect to their role in the pathogenesis of the neurodegenerative disorders of AD and of their potential use as markers. Enzymatic changes have been studied comparing AD patients with non AD controls as well as with AD relatives: proteases and their inhibitors; plasminogen activators; transketolases; increases in the activity of Cu-Zn superoxide dismutase in AD patients' RBC, serum, fibroblasts and cortical neurons, pointing to alterations in oxidative processes; and apolipoprotein E epsilon 4 allele, linked to late-onset AD and familial cases. This review presents reasons why the involvement of peripheral markers in AD should advance from hypothesis to accepted fact.

Copper-zinc superoxide dismutase activity in red blood cells in probable Alzheimer's patients and their first-degree relatives.

The activity of the enzyme copper-zinc superoxide dismutase (Cu-Zn SOD) has been investigated in red blood cell (RBC) homogenate obtained from demented patients with probable Alzheimer's disease (DAT), from their first-degree relatives (sisters/brothers and sons/daughters), and from healthy control families of the same age. A statistically significant increase in SOD activity (P < 0.01) was found in RBC's homogenate between families of DAT patients (not including the demented individual) and control families. Variability in SOD activity due to differences between families was not significant for DAT relatives; a significant variance component (P < 0.05) was found between control families. Additionally, a statistically significant increase in SOD activity (P < 0.001) with age in DAT patients up to 70 years and a significant decrease above this age were found, confirming a previously found relation. No changes in SOD activity with age were detected in healthy controls nor in DAT relatives. The increased levels of Cu-Zn SOD, probably represent a general alteration of the oxidative processes characteristic of this dementia and support the proposal that the enzyme could be used as an early diagnostic peripheral marker of the Alzheimer's disease (AD), and to determine to which subgroup the patient belongs, as well as a risk factor in non-demented first-degree relatives.

Copper-zinc superoxide dismutase activity in red blood cells and serum in demented patients and in aging.

The activity of the enzyme copper-zinc superoxide dismutase (Cu-Zn SOD) has been investigated in serum and red blood cells (RBC) homogenate obtained from demented patients with associated vascular lesions (VD), demented patients with probable Alzheimer's disease (DAT) and healthy controls (CG) of the same age. The increase in SOD activity was statistically significant (P < 0.01) in RBCs homogenate of DAT and VD patients, when compared to controls, but no differences appear between the two diseases groups. Additionally, a statistically significant increase in SOD activity (P < 0.01) in DAT patients above 70 years as compared to those 50-70 years old, and a relation between SOD and age were found. No changes in SOD activity with age in healthy controls nor in vascular dementia group were detected. A statistically significant increase in Circulating SOD activity (P < 0.01) was observed in vascular patients compared to controls. The observed increase in DAT Circulating SOD activity (against CG) was not significant. The increased levels of Cu-Zn SOD, probably represent a general alteration of the oxidative processes characteristic of these dementias and suggest that the enzyme might be used as a marker.

Effects of ketoconazole on the iodide uptake by FRTL-5 cells.

Ketoconazole is an imidazole derivative used as an antimycotic agent with reported effects on the endocrine system, but very little is known about its possible actions on thyroid function. Our purpose was to study the influence of this substance on the basal and TSH-stimulated iodide uptake in the rat thyroid cell strain FRTL-5. Ketoconazole (1-50 mumol/l) was shown to slightly increase the basal iodide uptake but, at higher concentrations (75-100 mumol/l), it sharply decreased iodide uptake below the basal levels. When the cells were cultured under bTSH stimulation (30 UI/l), the inhibitory effect of ketoconazole was exerted at concentrations as low as 25 mumol/l. This inhibition was observed even if it was added to the culture medium immediately before the Na125I addition. Forskolin, a stimulator of adenylate cyclase activity, was unable to prevent the iodide uptake inhibition. Low doses of ketoconazole increased cAMP concentrations. In the presence of TSH this effect was more evident in an inverse dose-dependent way. Because of its dual action, it can be assumed that ketoconazole could influence the iodide uptake in the FRTL-5 cells through more than one mechanism.

[Immunoregulation of tumor growth in a murine model]. / Inmunorregulación del crecimiento tumoral en un sistema murino.

Different spleen and tumor cell factors modifying tumoral and metastatic growth were studied. Spleen cell culture supernatants (SCS) from small and large tumor-bearing mice enhanced tumor growth. After tumor surgery, tumor enhancement was only mediated by supernatants from large tumor resected mice. Tumor facilitation and angiogenic response were mediated by the same supernatants; different fractions for these two activities were characterized. T and non-T cells, depending on tumor burden, were responsible for the enhancing activity; but angiogenesis depended only on T cells. While augmentation of metastatic spread was produced by tumor antigens (soluble tumor extracts, tumor-cell supernatants, formolized tumor cells), primary tumor development was not modified by tumor-cell supernatants. Increased incidence of metastases was also mediated by SCS from tumor resected mice which had previously been inoculated with tumor antigens. Immune status of tumor-resected mice was evaluated by delayed-type hypersensitivity reaction. Tumor cell membranes enriched with cholesterol-hemisuccinate were able to increase anti-tumor immune response.

Inmunorregulación del crecimiento tumoral en un sistema murino. / [Immunoregulation of tumor growth in a murine model]

Different spleen and tumor cell factors modifying tumoral and metastatic growth were studied. Spleen cell culture supernatants (SCS) from small and large tumor-bearing mice enhanced tumor growth. After tumor surgery, tumor enhancement was only mediated by supernatants from large tumor resected mice. Tumor facilitation and angiogenic response were mediated by the same supernatants; different fractions for these two activities were characterized. T and non-T cells, depending on tumor burden, were responsible for the enhancing activity; but angiogenesis depended only on T cells. While augmentation of metastatic spread was produced by tumor antigens (soluble tumor extracts, tumor-cell supernatants, formolized tumor cells), primary tumor development was not modified by tumor-cell supernatants. Increased incidence of metastases was also mediated by SCS from tumor resected mice which had previously been inoculated with tumor antigens. Immune status of tumor-resected mice was evaluated by delayed-type hypersensitivity reaction. Tumor cell membranes enriched with cholesterol-hemisuccinate were able to increase anti-tumor immune response.

Nature of the spleen cell populations capable of releasing tumor enhancing factor.

Supernatants obtained from short-cultured spleen cells (SCS) from BALB/c mice bearing a syngeneic mammary transplanted tumor--S13--showed enhancing activity on tumor growth when inoculated into the foot pad of normal syngeneic mice 24 hr before injection of S13 tumor cells. The present work was designed to characterize the spleen cell population responsible for the releasing of the enhancing factor (EF) as long as the tumor grows (small tumor bearing mice--STBM--and large tumor bearing mice--LTBM). Pretreatment of spleen cells with anti-Thy 1.2 serum + C' and nylon-wool columns were utilized to separate cell populations and to characterize the cellular source of the enhancing activity in the spleens of STBM and LTBM. In this tumor system, evidence is presented for distinct enhancing cell population operating in the spleens of STBM and LTBM. In early stages of tumor development, the EF was found to be associated with T and non-T cells, whereas in advanced stages of tumor growth, this activity was found to be associated with only T cells.