Decreased constitutive nitric oxide synthase, but increased inducible nitric oxide synthase and endothelin-1 immunoreactivity in aortic endothelial cells of donryu rats on a cholesterol-enriched diet

The Donryu rat is resistant to a high cholesterol diet in that typical atheromatous lesions do not develop. Using electron microscopic immunocytochemical techniques, the effects of a CCT diet (4% cholesterol with 1% cholic acid and 0.5% thiouracil) on the distributions of neuronal, macrophage, and endothelial specific nitric oxide synthase (NOS I, NOS II, and NOS III) and endothelin-1 (ET-1) immunoreactivity were examined in the thoracic aortic intima. Atheromatous lesions were absent, but immunocytochemistry showed 1. 4+/-0.52% and 4.0+/-0.9% endothelial cells (EC) with positive staining for NOS I and NOS III, respectively, compared with 16.3+/-2. 5% and 88.6+/-2.48% in control Donryu rats. The CCT-supplemented diet induced expression of NOS II immunoreactivity in thoracic aortic intimal cells. EC, subendothelial macrophages, and smooth muscle cells (SMC) also showed high NOS II-positive staining. The percentage of NOS II-immunoreactive EC was 43+/-1.8%. In control groups, no NOS II immunoreactive cells were observed. The percentage of ET-1 immunopositive cells was also significantly increased by 9. 2+/-0.66% and 64.2+/-1.4% in control and CCT-fed groups, respectively. It is concluded that the administration of a high cholesterol diet in Donryu rats produces endothelial dysfunction associated with changes in the balance of the different isoforms of NOS and ET-1. Therefore, the increase in inducible NOS and ET-1 immunoreactivity seen during the cholesterol-enriched diet appears to be a compensatory reaction of aortic wall cells to the high cholesterol supplementation.

Postradiotherapy prostate biopsies: what do they really mean? Results for 498 patients

PURPOSE

Postradiotherapy (RT) prostate biopsies are prone to problems in interpretation. False negatives due to sampling error, false positives due to delayed tumor regression, and indeterminate biopsies showing radiation effect in residual tumor of uncertain viability are common occurrences.

METHODS AND MATERIALS

A cohort of 498 men treated with conventional RT from 06/87-10/96 were followed prospectively with systematic transrectal ultrasound (TRUS)-guided post-RT prostate biopsies, starting 12-18 months after RT. If there was residual tumor but further decline in serum prostate-specific antigen (PSA), biopsies were repeated every 6-12 months. Patients with negative biopsies were rebiopsied at 36 months. Residual tumor was evaluated for RT effect and proliferation markers. The 498 men had 978 biopsies. Median time of the first biopsy (n = 498) was 13 months, biopsy #2 (n = 342) 28 months, biopsy #3 (n = 110) 36 months, biopsy #4 (n = 28) 44 months, and biopsy #5 (n = 4) 55 months. Median follow-up is 54 months (range 13-131). One hundred seventy-five patients (34%) had prior hormonal therapy for a median of 5 months (range 1-60).

RESULTS

Clinical stage distribution was T1b: 46; T1c: 50; T2a: 115; T2b/c: 170; T3: 108; T4: 11; Tx: 1. Distribution by Gleason score was: 28% Gleason score 2-4; 42%: 5-6; 18%: 7; and 12%: 8-10. Seventy-one men have died, 26 of prostate cancer and 45 of other causes. Actuarial failure-free survival by T stage at 5 years is T1b: 78%; T1c: 76%; T2a: 60%; T2b/c: 55%; T3: 30%; and T4: 0%. Actuarial freedom from local failure at 5 years is T1b: 83%; T1c: 88%; T2a: 72%; T2b/c: 66%; T3: 58%; and T4: 0%. The proportion of indeterminate biopsies decreases with time, being 33% for biopsy 1, 24% for biopsy 2, 18% for biopsy 3, and 7% for biopsy 4. Thirty percent of indeterminate biopsies resolved to NED status, regardless of the degree of RT effect, 18% progressed to local failure, and 34% remained as biopsy failures with indeterminate status within the time frame of this report. Positive staining for proliferation markers was associated with both subsequent local failure and also any type of failure. In multivariate analysis, only PSA nadir (p = 0.0002) and biopsy status at 24-36 months (p = 0. 0005) were independent predictors of outcome.

CONCLUSIONS

Post-RT prostate biopsies are not a gold standard of treatment efficacy, but are an independent predictor of outcome. Positive immunohistochemical staining for markers of cellular proliferation is associated with subsequent local failure. Indeterminate biopsies, even when showing marked RT effect, cannot be considered negative.

In Alzheimer's disease, heme oxygenase is coincident with Alz50, an epitope of tau induced by 4-hydroxy-2-nonenal modification

In this study, we compared the neuronal induction of the antioxidant heme oxygenase-1 (HO-1) in Alzheimer's disease with abnormalities in tau marked by antibodies recognizing either phosphorylation (AT8) or conformational change (Alz50). The epitope recognized by Alz50 shows a complete overlap with HO-1-containing neurons, but AT8 recognized these neurons as well as neurons not displaying HO-1. These findings suggest that tau phosphorylation precedes the HO-1 response and that HO-1 is coincident with the Alz50 epitope. This led us to consider whether oxidative damage plays a role in forming the Alz50 epitope. We found that 4-hydroxy-2-nonenal (HNE), a highly reactive product of lipid peroxidation, reacts with normal tau and induces the Alz50 epitope in tau. It is important that the ability of HNE to create the Alz50 epitope not only is dependent on lysine residues of tau but also requires tau phosphorylation because neither methylated, recombinant, nor dephosphorylated tau reacts with HNE to create the Alz50 epitope. Supporting the in vivo relevance of this observation, endogenous paired helical filament-tau isolated from subjects with Alzheimer's disease was immunoreactive with an antibody to a stable HNE-lysine adduct, as were all vulnerable neurons in subjects with Alzheimer's disease but not in control individuals. Together, these findings support the involvement of oxidative damage early in neurofibrillary tangle formation in Alzheimer's disease and also suggest that HNE modification contributes to the generation of the tau conformation defining the Alz50 epitope. These findings provide evidence that an interplay between phosphorylation of tau and neuronal oxidative stress-induced pathology is important in the formation of neurofibrillary tangles.

Sequestration of iron by Lewy bodies in Parkinson's disease

Central to the oxidative stress hypothesis of Parkinson's disease (PD) pathogenesis is the ability of iron to generate hydroxyl radicals via the Fenton reaction, and the consistent demonstration of iron elevation in the pars compacta region of the substantia nigra. However, uncertainty exists as to whether the excess iron exists in a state suitable for redox chemistry. Here, using a method we developed that detects redox-active iron in situ, we were able to demonstrate strong labeling of Lewy bodies in substantia nigra pars compacta neurons in PD. In contrast, cortical Lewy bodies in cases of Lewy body variant of Alzheimer's disease were unstained. While the presence of elevated iron in PD substantiates the oxidative stress hypothesis, one must remember that these are viable neurons, indicating that Lewy bodies may act to sequester iron in PD brains in a protective, rather than degenerative, mechanism. The absence of redox-active iron in neocortical Lewy bodies highlights a fundamental difference between cortical and brain stem Lewy bodies.

Prepregnancy body mass index and pregnancy weight gain: associations with preterm delivery. The NMIHS Collaborative Study Group

OBJECTIVE

To examine associations between rate of pregnancy weight gain and preterm delivery among women of varying prepregnancy body mass indices (BMI).

METHODS

Subjects were 3511 mother-infant pairs from the 1988 National Maternal and Infant Health Survey. Prenatal weight measured between 14 and 28 weeks' gestation was used to calculate rate of pregnancy weight gain for each woman. Weight gain (lb/week) was categorized as low (under 0.5), average (0.5-1.5), or high (above 1.5). Prepregnancy BMI was calculated as weight divided by height in (kg/m(2)) and categorized as low (under 19.8), average (19.8-26.0), and high (above 26). Delivery before 37 weeks' gestation was considered preterm. Associations between BMI, weight gain, and preterm delivery were examined before and after exclusion of medically indicated preterm deliveries and pregnancies complicated by maternal medical conditions potentially related to weight gain or fetal growth restriction. Associations were expressed as odds ratios (OR) adjusted for several potential confounding factors.

RESULTS

Women with low pregnancy weight gain were at increased risk of preterm delivery. The magnitude of risk varied according to a woman's prepregnancy BMI. After all exclusions and adjustments for confounders, ORs, and 95% confidence intervals (CI) for low pregnancy weight gain were 6.7 (1.1, 40.6) for underweight women, 3.6 (1.6, 8.0) for average-weight women, and 1.6 (0.7, 3.5) for overweight women compared with average-weight women with average pregnancy weight gain.

CONCLUSIONS

Low weight gain in pregnancy was associated with increased risk of preterm delivery, particularly if women were underweight or of average weight before pregnancy.

Oxidative stress in Alzheimer's disease

Oxidative balance is emerging as an important issue in understanding the pathogenesis of Alzheimer's disease. Examination of Alzheimer's disease brain has demonstrated a great deal of oxidative damage, associated with both hallmark pathologies (senile plaques and neurofibrillary tangles) as well as in normal appearing pyramidal neurons. While this suggests that oxidative stress is a proximal event in Alzheimer's disease pathogenesis, the mechanisms by which redox balance is altered in the disease remains elusive. Determining which of the proposed sources of free radicals, which include mitochondrial dysfunction, amyloid-beta-mediated processes, transition metal accumulation and genetic factors like apolipoprotein E and presenilins, is responsible for redox imbalance will lead to a better understanding of Alzheimer's disease pathogenesis and novel therapeutic approaches.

Oxidative damage in Alzheimer's disease: the metabolic dimension

Cell bodies of neurons at risk of death in Alzheimer disease have increased lipid peroxidation, nitration, free carbonyls, and nucleic acid oxidation. These oxidative changes are uniform among neurons and are seen whether or not the neurons display neurofibrillary tangles and, in fact, are acutally reduced in the latter case. In consideration of this localization of damage, in this review, we provide a summary of recent work demonstrating some key abnormalities that may initiate and promote neuronal oxidatave damage.

Evidence that the beta-amyloid plaques of Alzheimer's disease represent the redox-silencing and entombment of abeta by zinc

Abeta binds Zn(2+), Cu(2+), and Fe(3+) in vitro, and these metals are markedly elevated in the neocortex and especially enriched in amyloid plaque deposits of individuals with Alzheimer's disease (AD). Zn(2+) precipitates Abeta in vitro, and Cu(2+) interaction with Abeta promotes its neurotoxicity, correlating with metal reduction and the cell-free generation of H(2)O(2) (Abeta1-42 > Abeta1-40 > ratAbeta1-40). Because Zn(2+) is redox-inert, we studied the possibility that it may play an inhibitory role in H(2)O(2)-mediated Abeta toxicity. In competition to the cytotoxic potentiation caused by coincubation with Cu(2+), Zn(2+) rescued primary cortical and human embryonic kidney 293 cells that were exposed to Abeta1-42, correlating with the effect of Zn(2+) in suppressing Cu(2+)-dependent H(2)O(2) formation from Abeta1-42. Since plaques contain exceptionally high concentrations of Zn(2+), we examined the relationship between oxidation (8-OH guanosine) levels in AD-affected tissue and histological amyloid burden and found a significant negative correlation. These data suggest a protective role for Zn(2+) in AD, where plaques form as the result of a more robust Zn(2+) antioxidant response to the underlying oxidative attack.

Activation of NADPH oxidase in Alzheimer's disease brains

The present study is the first to show that superoxide (O(-)(2)) forming NADPH oxidase is activated in Alzheimer's disease (AD) brains by demonstrating the marked translocation of the cytosolic factors p47-phox and p67-phox to the membrane. In conjunction with a recent in vitro study showing that amyloid beta activates O(-)(2) forming NADPH oxidase in microglia, where these phox proteins are localized in this study, the present results suggest that, in AD, NADPH oxidase is activated in microglia, resulting in the formation of reactive oxygen species which can be toxic to neighboring neurons in AD.

The role of metals in neurodegenerative diseases

There is increasing evidence in a number of neurodegenerative diseases that transition metal-mediated abnormalities play a crucial role in disease pathogenesis. In this treatise, we review the role of metal homeostasis as it pertains to alterations in brain function in neurodegenerative diseases. In fact, while there is documented evidence for alterations in transition metal homeostasis, redox-activity and localization, it is also important to realize that alterations in specific copper- and iron-containing metalloenzymes also appear to play a crucial role in the neurodegenerative process.

Lipoperoxidation is selectively involved in progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is a neurodegenerative disorder characterized by extensive neurofibrillary tangle (NFT) formation and neuronal loss in selective neuronal populations. Currently, no clues to the biological events underlying the pathological process have emerged. In Alzheimer disease (AD), which shares with PSP the occurrence of NFTs, advanced glycation end products (AGEs) as well as oxidation adducts have been found to be increased in association with neurofibrillary pathology. The presence and the amount of lipid and protein oxidation markers, as well as of pyrraline and pentosidine. 2 major AGEs, was assessed by biochemical, immunochemical, and immunocytochemical analysis in midbrain tissue from 5 PSP cases, 6 sporadic AD cases, and 6 age-matched control cases. The levels of 4-hydroxynonenal (HNE) and thiobarbituric acid reactive substances (TBARS), 2 major products of lipid peroxidation, were significantly increased by 1.6-fold (p < 0.04) and 3.9-fold (p < 0.01), respectively, in PSP compared with control tissues, whereas in AD only TBARS were significantly increased. In PSP tissue the intensity of neuronal HNE immunoreactivity was proportional to the extent of abnormal aggregated tau protein. The amount of protein oxidation products and AGEs was instead similar in PSP and control tissues. In AD, a higher but not significant level of pyrraline and pentosidine was measured, whereas the level of carbonyl groups was doubled. These findings indicate that in PSP, unlike in AD, lipid peroxidation is selectively associated with NFT formation. The intraneuronal accumulation of toxic aldehydes may contribute to hamper tau degradation, leading to its aggregation in the PSP specific abnormal filaments.

Prospects for noninvasive imaging of brain amyloid beta in Alzheimer's disease

The brain in patients with Alzheimer's disease (AD) contains large amounts of fibrillary amyloid beta protein. Studies attempting to use levels of amyloid beta protein in plasma, cerebrospinal fluid or skin as diagnostic tests for the disease have not been fruitful. A method for the noninvasive detection of cerebral amyloid beta would be valuable for dementia differential diagnosis, pathophysiology and monitoring of anti-amyloid therapies. Anti-amyloid monoclonal antibody 10H3 has been evaluated as an amyloid-imaging ligand, without success. Important considerations in the development of amyloid-imaging ligands include choice of radiolabel and physical and biological half-lives, route of administration, protein binding, use of control molecules, and imaging techniques. It is important that imaging studies be designed to reflect the slow nature of the process of amyloid deposition. We used a transgenic mouse model overexpressing beta protein precursor (beta PP) to assess the binding of basic fibroblast growth factor (bFGF) and serum amyloid P component (SAP) to amyloid beta (A beta) plaques in mouse brain. Although the binding of these ligands is similar to AD, neither is found endogenously associated with A beta deposits. Because SAP is a component of mouse serum, these findings suggest the blood-brain barrier in transgenic mice is not affected as it is in AD. These findings suggest that the transgenic mouse may be used as a model for evaluation of A beta imaging methods.

Quinone reductase (NQO1), a sensitive redox indicator, is increased in Alzheimer's disease

NAD(P)H:quinone oxidoreductase 1 (NQO1), a redox-regulated flavoenzyme, plays a central role in monitoring cellular redox state. NQO1 acts to protect against oxidative stress induced by a variety of metabolic situations, including metabolism of quinones and other xenobiotics, by: (i) functioning as a two electron donor to provide a shunt that competes with the formation of reactive oxygen species; (ii) maintaining reduced coenzyme Q; and (iii) regulating the stress activated kinase pathway. In Alzheimer's disease, while there is abundant evidence for the involvement of oxidative stress, the cause or the consequences are largely unresolved. We suspected that increased NQO1 could signal a major shift in redox balance in Alzheimer's disease and, in this study, found that NQO1 is localized not only to neurofibrillary tangles but also the cytoplasm of hippocampal neurons. By marked contrast, there is very little NQO1 in the same neuronal populations in young and age-matched controls. This novel association of NQO1 further buttresses the nexus of oxidative stress, via free radicals, with selective neuronal vulnerability and also supports a fundamental abnormality in redox balance in Alzheimer's disease.

Felodipine improves left ventricular emptying in patients with chronic heart failure: V-HeFT III echocardiographic substudy of multicenter reproducibility and detecting functional change

BACKGROUND

The echocardiographic substudy of the Vasodilator-Heart Failure Trial III (V-HeFT III) aimed to determine if felodipine treatment in patients with heart failure who were taking an angiotensin-converting enzyme inhibitor had a favorable effect on left ventricular (LV) structure and function. Earlier V-HeFT trials showed that hydralazine-isosorbide dinitrate improved ejection fraction (EF) and survival, whereas enalapril achieved greater survival with smaller increases in EF. Would the combination of a potent vasodilator and enalapril produce greater improvements in function and survival?

METHODS AND RESULTS

Doppler-echocardiographic data were collected from 260 males with heart failure who were randomized to felodipine or a placebo. Mean intrasubject differences between baseline, at 3 months, and at 12 months were compared. Intersite and intrareader reproducibilities were measured from duplicate recordings and readings. At 3 months, no changes in ultrasound variables from baseline occurred in either group. At 12 months, felodipine patients achieved greater increases in EF, shortening of LV end-systolic length, and increases in stroke volume index. Reproducibility coefficients of variation were 7.4% (EF), 6.0% (end-diastolic length), and 13.0% (stroke volume index).

CONCLUSIONS

The echocardiographic substudy showed that felodipine, added to heart failure therapy, increased EF, shortened end-systolic length, and increased stroke volume index. The changes were small and confirmed that reproducibility from multiple laboratories can be coordinated into a useful research tool.

Vascular abnormalities: the insidious pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) and cerebrovascular dementia (CVD) are two major causes of senile dementia in elderly individuals. Mounting evidence from epidemiological, clinical, and neuropathological studies suggests that there is considerable overlap between AD and CVD with respect to risk factors, prevalence, and pathological changes. Although our lack of understanding on the important contribution of vascular disturbance to pathogenesis of AD has further hindered our understanding of AD, data on the roles of cerebrovascular diseases and systemic vascular diseases in AD need to be carefully analyzed to avoid misinterpretation. Here, we review studies on the cerebral vasculature, cardiac vasculature, and apoE that lead us to contend that vascular abnormalities are likely an important mechanism underlying dementia. Because early and aggressive intervention is available to prevent and treat a number of vascular diseases, therapies that attenuate vascular risk factors could be valuable in preventing and treating AD.

Overexpression of heme oxygenase in neuronal cells, the possible interaction with Tau

Increased expression of heme oxygenase-1 (HO-1) is a common feature in a number of neurodegenerative diseases. Interestingly, the spatial distribution of HO-1 expression in diseased brain is essentially identical to that of pathological expression of tau. In this study, we explored the relationship between HO-1 and tau, using neuroblastoma cells stably transfected with sense and antisense HO-1 constructs as well as with the vector alone. In transfected cells overexpressing HO-1, the activity of heme oxygenase was increased, and conversely, the level of tau protein was dramatically decreased when compared with antisense HO-1 or CEP transfected cells. The suppression of tau protein expression was almost completely reversed by zinc-deuteroporphyrin, a specific inhibitor of heme oxygenase activity. The activated forms of ERKs (extracellular signal-regulated kinases) were also decreased in cells overexpressing HO-1 although no changes in the expression of total ERK-1/2 proteins were observed. These data are in agreement with the finding that the expression of tau is regulated through signal cascades including the ERKs, whose activities are modulated by oxidative stresses. The expression of tau and HO-1 may be regulated by oxidative stresses in a coordinated manner and play a pivotal role in the cytoprotection of neuronal cells.

Histochemical and immunocytochemical approaches to the study of oxidative stress

We review an array of newly developed in situ detection methods that can be used for the qualitative and semi-quantitative measurement of various indices related to oxidative stress. The importance of in situ methods over bulk analysis cannot be overstated when considering the structural and cellular complexity of tissue and the effects of diseases thereof. Indeed, in situ detection allows detection of specific cell types affected or specific localization such that a process affecting only a small fraction of the tissue or cells can be readily visualized. Consequently, a positive signal in situ indicates real levels that cannot be masked by unrelated or compensatory responses in adjacent cells, and corrections can be easily made for the modifications to long-lived proteins during physiological aging. In fact, the damage to extracellular matrix proteins of major vessels, provides a cumulative record of long-term oxidative insult. Yet the same properties that make vessels ideal markers for aging limits their sensitivity to detect disease-specific changes unless in situ techniques are used.