Associations between gonadotropins, testosterone and ß amyloid in men at risk of Alzheimer's disease.

Testosterone and gonadotropins have been associated with cognitive decline in men and the modulation of ß amyloid (Aß) metabolism. The relatively few studies that have investigated whether changes in one or a combination of these hormones influence Aß levels have focused primarily on plasma Aß(1-40) and not on the more pathogenic Aß(1-42). Currently, no study has investigated whether these hormones are associated with an increase in brain amyloid deposition, ante mortem. Through the highly characterised Australian imaging, biomarkers and lifestyle study, we have determined the impact of these hormones on plasma Aß levels and brain amyloid burden (Pittsburgh compound B (PiB) retention). Spearman's rank correlation and linear regression analysis was carried out across the cohort and within subclassifications. Luteinizing hormone (LH) was the only variable shown, in the total cohort, to have a significant impact on plasma Aß(1-40) and Aß(1-42) levels (beta=0.163, P<0.001; beta=0.446, P<0.001). This held in subjective memory complainers (SMC) (Aß(1-40); beta=0.208, P=0.017; Aß(1-42); beta=0.215, P=0.017) but was absent in mild cognitive impairment (MCI) and Alzheimer's disease (AD) groups. In SMC, increased frequency of the APOE-ɛ4 allele (beta=0.536, P<0.001) and increasing serum LH levels (beta=0.421, P=0.004) had a significant impact on PiB retention. Whereas in MCI, PiB retention was associated with increased APOE-ɛ4 allele copy number (beta=0.674, P<0.001) and decreasing calculated free testosterone (beta=-0.303, P=0.043). These findings suggest a potential progressive involvement of LH and testosterone in the early preclinical stages of AD. Furthermore, these hormones should be considered while attempting to predict AD at these earliest stages of the disease.

Sensitivity of the Preclinical Alzheimer's Cognitive Composite (PACC), PACC5, and Repeatable Battery for Neuropsychological Status (RBANS) to Amyloid Status in Preclinical Alzheimer's Disease -Atabecestat Phase 2b/3 EARLY Clinical Trial.

BACKGROUND: Cognitive composites commonly serve as primary outcomes in Alzheimer's disease (AD) secondary prevention trials. OBJECTIVE: To evaluate the association between amyloid (Aß) burden level (+/-) and performance on three separate composite endpoints: Preclinical Alzheimer's Cognitive Composite (PACC), PACC+Semantic Fluency (PACC5), and Repeatable Battery for Neuropsychological Status (RBANS). DESIGN: Screening data from the randomized, double-blind, placebo-controlled, phase 2b/3 atabecestat EARLY study in preclinical AD participants were used in this analysis. SETTING: The EARLY study was conducted at 143 centers across 14 countries. PARTICIPANTS: 3,569 cognitively unimpaired older adults (Clinical Dementia Rating of 0; aged 60-85 years) screened for inclusion in the EARLY study with Aß status and at least PACC or RBANS at screening were included. Participants were categorized as those with non-pathological Aß levels (Aß-, n=2,824) and those with pathological Aß levels (Aß+, n=745) based on florbetapir uptake or levels of cerebrospinal fluid Aß1-42. MEASUREMENTS: Analysis of Covariance models controlling for age, sex, and education were used to examine the difference in PACC, PACC5, and RBANS between Aß groups. Nonparametric bootstrap was used to compare sensitivity of composites to differentiate between Aß status. RESULTS: Of 3,569 participants, 2,116 were women (59%); 3,006 were Caucasian (84%); mean (SD) age was 68.98 (5.28) years. Aß+ participants performed worse versus Aß- participants on all cognitive composites though the magnitude of the Aß effect was generally small. The Aß+/- effect size for the PACC (Cohen's d=-0.15) was significantly greater than the RBANS (d=-0.097) while the PACC5 effect size (d=-0.139) was numerically larger than the RBANS. When examining subscores from the composites, memory tests (i.e., Free and Cued Selective Reminding Test, Figure Recall) and speed of processing (i.e., Digit-Symbol/Coding on the PACC/RBANS) exhibited the largest Aß+/- effect sizes. CONCLUSIONS: Cross-sectional relationships between Aß and cognition among clinically unimpaired older adults are detectable on multi-domain cognitive composites but are relatively small in magnitude. The Aß+/- group effect was statistically larger for PACC and marginally larger for PACC5 versus RBANS. However, interpretation of composite sensitivity to Aß status cross-sectionally cannot be generalized to sensitivity to change over time.

Paclitaxel induced apoptosis in breast cancer cells requires cell cycle transit but not Cdc2 activity.

PURPOSE: Paclitaxel (PTX) is a widely used chemotherapy agent and may cause cell death by apoptosis subsequent to microtubule (MT) disruption. In this paper, we have investigated whether cell cycle transit and or Cdc2 (Cdk1) activity is required for the apoptosis induced by PTX. METHODS: Cell cycle was analyzed by flow cytometry, Cdc2 was assayed bio chemically. Cdc2 activity was decreased by siRNA and dominant negative (dn) Cdc2 expression. Cells were arrested by chemical or biological inhibitors in a G1 or S phase. Apoptosis was measured by DNA fragmentation and examination of nuclei by microscopy. JNK and AKT activations were assessed as well. RESULTS: Cell cycle inhibition was highly effective in decreasing PTX induced apoptosis. MT morphology was not altered by these inhibitors. PTX induced JNK activity or AKT mediated BAD phosphorylation was unaffected by cell cycle inhibitors. Abrogation of Cdc 2 activity was without effect on PTX induced apoptosis. CONCLUSIONS: While cell cycle transit is required for PTX induced apoptosis; Cdc2 activity is not required.

Multifaceted regulation of cell cycle progression by estrogen: regulation of Cdk inhibitors and Cdc25A independent of cyclin D1-Cdk4 function.

Estrogens induce proliferation of estrogen receptor (ER)-positive MCF-7 breast cancer cells by stimulating G(1)/S transition associated with increased cyclin D1 expression, activation of cyclin-dependent kinases (Cdks), and phosphorylation of the retinoblastoma protein (pRb). We have utilized blockade of cyclin D1-Cdk4 complex formation through adenovirus-mediated expression of p16(INK4a) to demonstrate that estrogen regulates Cdk inhibitor expression and expression of the Cdk-activating phosphatase Cdc25A independent of cyclin D1-Cdk4 function and cell cycle progression. Expression of p16(INK4a) inhibited G(1)/S transition induced in MCF-7 cells by 17-beta-estradiol (E(2)) with associated inhibition of both Cdk4- and Cdk2-associated kinase activities. Inhibition of Cdk2 activity was associated with delayed removal of Cdk-inhibitory activity in early G(1) and decreased cyclin A expression. Cdk-inhibitory activity and expression of both p21(Cip1) and p27(Kip1) was decreased, however, in both control and p16(INK4a)-expressing cells 20 h after estrogen treatment. Expression of Cdc25A mRNA and protein was induced by E(2) in control and p16(INK4a)-expressing MCF-7 cells; however, functional activity of Cdc25A was inhibited in cells expressing p16(INK4a). Inhibition of Cdc25A activity in p16(INK4a)-expressing cells was associated with depressed Cdk2 activity and was reversed in vivo and in vitro by active Cdk2. Transfection of MCF-7 cells with a dominant-negative Cdk2 construct inhibited the E(2)-dependent activation of ectopic Cdc25A. Supporting a role for Cdc25A in estrogen action, antisense CDC25A oligonucleotides inhibited estrogen-induced Cdk2 activation and DNA synthesis. In addition, inactive cyclin E-Cdk2 complexes from p16(INK4a)-expressing, estrogen-treated cells were activated in vitro by treatment with recombinant Cdc25A and in vivo in cells overexpressing Cdc25A. The results demonstrate that functional association of cyclin D1-Cdk4 complexes is required for Cdk2 activation in MCF-7 cells and that Cdk2 activity is, in turn, required for the in vivo activation of Cdc25A. These studies establish Cdc25A as a growth-promoting target of estrogen action and further indicate that estrogens independently regulate multiple components of the cell cycle machinery, including expression of p21(Cip1) and p27(Kip1).

Longitudinal Trajectories of Clinical Decline in Amyloid Positive and Negative Populations.

BACKGROUND: Brain beta-amyloid status portends different trajectories of clinical decline. OBJECTIVE: Determine trajectories and predictive baseline variable(s). DESIGN: Longitudinal, up to 24 months. SETTING: ADNI sites. PARTICIPANTS: Healthy control (n=325), early and late mild cognitive impairment (n=279; n=372), and Alzheimer's dementia (n=216) subjects from ADNI-1/GO/2. MEASUREMENTS: Baseline amyloid status was based on first available CSF Aß1-42 or, [11C]PiB or [18F]florbetapir (FBP) PET. Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog13) and Functional Activities Questionnaire (FAQ) were co-analyzed using Growth Mixture Modeling (GMM) to define latent class trajectories for each amyloid group. Classification and Regression Tree (CART) analysis determined which variables best predicted trajectory class membership using a number of variables available to clinicians. RESULTS: GMMs found two trajectory classes (C1, C2) each for amyloid-positive (P; n=722) and negative (N; n=470) groups. Most (90%) in the negative group were C2N with mildly impaired baseline ADAS-Cog13, normal FAQ and nonprogression; 10% were C1N with moderately impaired baseline FAQ and ADAS-Cog13 and trajectory of moderately worsening scores on the FAQ. C1P (26%) had more impaired baseline FAQ and ADAS-Cog13 than C2P (74%) and a steeper declining trajectory. CART yielded 4 decision nodes (FAQ <10.5, FAQ <6.5, MMSE ≥26.5, age <75.5) in positive and 1 node (FAQ <6.5) in negative groups, with 91.4% and 92.8% accuracy for class assignments, respectively. CONCLUSIONS: The trajectory pattern of greater decline in amyloid positive subjects was predicted by greater baseline impairment of cognition and function. While most amyloid-negative subjects had nonprogression irrespective of their diagnosis, a subgroup declined similarly to the gradually declining amyloid-positive group. CART predicted likely trajectory class, with known amyloid status, using variables accessible in a clinical setting, but needs replication.

Estrogens and cell-cycle regulation in breast cancer.

Clinical and experimental data have established that the leading cause of sporadic female breast cancer is exposure to estrogens, predominantly 17beta-estradiol. Recent advances in the understanding of cell-cycle control mechanisms have been applied to outline the molecular mechanisms through which estrogens regulate the cell cycle in cultured breast cancer cells, in particular, in MCF-7 cells. Here, we discuss how estrogens exert control over several key G1 phase cell-cycle regulators, namely cyclin D1, Myc, Cdk2, Cdk4, Cdk inhibitors and Cdc25A. Although the molecular mechanisms underlying estrogenic regulation of G1 phase regulators are far from clear, current evidence indicates that estrogens might regulate several key molecules required for S phase entry, this regulation being independent of cell-cycle transit per se.

The relative stability of selected herpes simplex virus type 1 mRNAs.

The relative stability of herpes simplex virus type 1 mRNAs was investigated by examination of the decay rates of selected viral transcripts. The synthesis of mRNA was inhibited by the addition of dactinomycin to HSV-1 infected cells, and the abundance of individual transcripts was determined at subsequent times by RNA blot hybridization. For two immediate-early mRNAs, those encoding the 110 and 63 kilodalton immediate-early proteins, RNA synthesis was inhibited at 3 h post-infection and mRNA half-lives of 5-7 h were found. Examination at 5 h post-infection of the early mRNA encoding thymidine kinase as well as the late mRNA encoding glycoprotein H revealed half-lives of 8-11 h. In contrast, at 12 h post-infection, the late mRNAs encoding the glycoproteins C, E, as well as H were found to have half-lives of 14-29 h. These findings suggest that the relative stability of viral mRNA increases late in infection and is dependent upon the time after infection rather than being strictly a property of the mRNA itself.

Carcinogenic potential of benzene and toluene when evaluated using cyclin-dependent kinase activation and p53-DNA binding.

Benzene is carcinogenic, whereas toluene is thought to have little carcinogenic potential. Benzene and toluene were found to activate cyclin-dependent kinase 2 in rat liver epithelial (RLE) and HL60 cells. pRb105 was hyperphosphorylated in RLE cells treated with either solvent. Kinase activation and subsequent hyperphosphorylation of pRb105 and p53 by benzene or toluene may be responsible for their growth promotional effects, but it does not account for increased potential of benzene to induce cancer. Therefore, we examined the ability of these solvents to increase p53-DNA site-specific binding in RLE cells. Benzene increased p53-DNA site-specific DNA binding in RLE cells compared to control levels or the effects of toluene. Increased p53-DNA site-specific binding by benzene may be caused by damage to cellular DNA. If so, although both solvents appear to have promotional activity, the increased potential of benzene to damage DNA may be responsible to the difference in the ability of benzene to cause cancer.

Estrogenic and DNA-damaging activity of Red No. 3 in human breast cancer cells.

Exposure to pesticides, dyes, and pollutants that mimic the growth promoting effects of estrogen may cause breast cancer. The pesticide DDT and the food colorant Red No. 3 were found to increase the growth of HTB 133 but not estrogen receptor (ER) negative human breast cells (HTB 125) or rat liver epithelial cells (RLE). Red No. 3, beta-estradiol, and DDT increase ER site-specific DNA binding to the estrogen response element in HTB 133 cells and increase cyclin-dependent kinase 2 activity in MCF-7 breast cancer cells. Site-specific DNA binding by p53 in RLE, HTB 125, HTB 133, and MCF-7 cells was increased when they were treated with Red No. 3, which suggests that cellular DNA was damaged by this colorant. Red No. 3 increased binding of the ER from MCF-7 cells to the estrogen-responsive element. Consumption of Red No. 3, which has estrogenlike growth stimulatory properties and may be genotoxic, could be a significant risk factor in human breast carcinogenesis.

Effects of 60-Hz fields, estradiol and xenoestrogens on human breast cancer cells.

If exposure to xenoestrogens or electromagnetic fields (EMFs) such as 60 Hz contributes to the etiology of breast cancer, it is likely that they must stimulate the growth of breast cells, damage genetic material or enhance the effects of other mitogenic or mutagenic agents (co-promotion). Therefore, the ability of xenoestrogens or exposure to 60-Hz fields to stimulate the entry of growth-arrested human breast cancer cells into the cell cycle was determined using cyclin-dependent kinase 2 (Cdk2) activity, synthesis of cyclin D1 and cdc2 activity. Exposure of estrogen receptor-positive MCF-7 or T-47D cells to estrogen and xenoestrogens (DDT and Red No. 3) increased Cdk2 and cyclin B1-cdc2 activity and cyclin D1 synthesis. Exposure of breast cancer cells to 12 mG or 1 or 9 G electromagnetic fields at 60 Hz failed to stimulate Cdk2 or cyclin B1-cdc2 activity or cyclin D1 synthesis. Simultaneous co-exposure of cells to 60-Hz fields and chemical promoters did not enhance Cdk2 activation above the levels produced by the chemical promoter alone. Estrogen and xenoestrogens also stimulated binding of the estrogen receptor to the estrogen receptor element but the EMF did not. Phorbol 12-myristate 13-acetate (PMA) induced phosphorylation of p53 and pRb1O5 in MCF-7 cells, but EMF exposure had no effect. DNA-damaging chemotherapeutic agents and Red Dye No. 3 were found to increase p53 site-specific DNA binding in breast cancer cells, but EMF exposure did not. Differential display analysis failed to detect any effect of EMF exposure on gene expression in MCF-7 cells, whereas the effects of estradiol were detected. These studies suggest that estrogen and xenoestrogens stimulate growth-arrested breast cancer cells to enter the growth cycle, but EMF exposure does not. Site-specific p53-DNA binding was increased in MC F-7 cells treated with DNA-damaging agents, but not by EMF exposure. EMF exposure does not appear to act as a promoter or DNA-damaging agent for human breast cancer cells in vitro.

Adrenal cortical carcinoma--a continuing challenge.

The records of 62 patients (36 female and 26 male) with pathologically confirmed adrenal cortical carcinoma who had operations between 1960 and 1980 were reviewed. The mean age was 48 years. There were 36 (58%) functioning tumors and 26 (42%) nonfunctioning tumors. Curative resection was performed in 31 patients, palliative resection in 14, and open biopsy alone in 17 with an overall operative mortality rate of 9.7% and a 5-year survival rate of 16%. There was no significant difference in survival rates between patients who had operations alone and those who had operations plus adjunctive therapy. Patients with stages I to III lesions or those who underwent curative resections had significantly longer survival than had those with stage IV disease or those who had palliative resections, respectively. Factors that failed to influence survival rates included palliative resection versus biopsy, tumor size, grade, function, and patient sex or age. We conclude that operative staging is prognostically valuable, aggressive surgical treatment is recommended in stages I to III lesions, and a prospective randomized study of adjuvant treatment for all stages of adrenal cortical carcinoma is indicated.

Psychometric modeling of consumer decisions in primary health care.

A psychometric technique, functional measurement, was used to measure the preferences of 77 persons for hypothetical health care providers identified by various levels of cost, travel time, and waiting time; responses were subjected to analysis of variance and graphic analysis to determine the functional relation by which respondents combined the three attributes in arriving at their preferences. Both modes of analysis suggested multiplicative decision models, but these yielded lower values of R2 than did linear models derived for comparison. Respondents were grouped by the proportion of response variance that was explained by each of the three attributes, and decision models were derived for each group. Discriminant analysis of socioeconomic characteristics of the respondents identified the variables that distinguished the groups and contributed to forming their preferences.

Malaria past and present: the case of North Sulawesi, Indonesia.

The incidence and impact of malaria in North Sulawesi have declined both in the short term during the 1990s, and over a much longer timespan (though perhaps less continuously) since the end of the colonial period. The improvement already seems to have been well underway before deliberate vector control activities became extensive in the second half of the 1970s, and environmental changes affecting the Anopheles mosquito fauna, in particular the replacement of primary and secondary forest by permanent farmland, are probably the principal reasons for the long-term trend; other possible factors include the increasing use of antimalarial drugs. The well-documented decline in malaria incidence over the years 1991-1997, nevertheless, probably reflects the unprecedented scale of residual insecticide spraying in the province during that period, while the slight resurgence of the disease in the last three years corresponds to the subsequent cessation of house spraying as a result of the current economic crisis. Despite the evident importance of environmental change as a factor ameliorating the malaria situation in the long term, experience from the colonial era suggests that the prospects for deliberate environmental management (species sanitation) as an alternative malaria control strategy are poor.

New insights into corticosteroid-binding globulin and glucocorticoid delivery.

Corticosteroid-binding globulin (CBG) binds cortisol with high affinity and facilitates its transport in the blood. A recent discovery suggests that CBG may have a role beyond that of a simple transport carrier protein. CBG functions as a protein thermocouple that is exquisitely sensitive to temperature change, releasing cortisol in response to increasing temperatures within the human physiological range. It is also expressed in the human hypothalamus and cerebrospinal fluid, while in the rodent it is also found in other intracellular neuronal locations, suggesting a role in regulating access of glucocorticoids to their receptors in the CNS. Genetic variants of CBG have been detected in man and have been associated with fatigue-pain syndromes and hypotension, again suggesting a potential effect of CBG on the access of cortisol to brain glucocorticoid receptors. These new findings provide the basis for a novel concept of the mechanisms through which the body regulates access of glucocorticoids to the brain and other tissues of the body.

Novel corticosteroid-binding globulin variant that lacks steroid binding activity.

BACKGROUND: Corticosteroid-binding globulin (CBG) is the principal carrier for glucocorticoids in the circulation and a regulator of their bioavailability. Inherited CBG deficiencies are rarely reported, and only three causative mutations in four families have been described. PATIENTS, METHODS, AND RESULTS: In a 26-yr-old female with hypotension, fatigue, and undetectable total serum cortisol at presentation, we have identified a novel homozygous c.776g>t transversion in exon 3 of the CBG (SERPINA6) gene. This results in a p.Gly237Val substitution that is predicted to influence the positioning of two ß-sheets that constitute part of the CBG steroid-binding site. Two siblings were also homozygous for the variant, whereas her mother and an unaffected sibling were heterozygous. No other symptomatic family members were identified apart from the proband. Individuals homozygous for the variant had serum CBG levels below the reference range when measured by RIA, but CBG was unmeasurable in cortisol-binding capacity assays. In the same individuals, we observed very low baseline and stimulated total serum cortisol levels but normal free serum and salivary cortisol and plasma ACTH. In a study of ultradian cortisol pulsatility, increased pulse frequency was only observed in the proband. CONCLUSION: We describe a novel CBG variant that lacks steroid binding activity. All mutant homozygotes have very low total serum cortisol, but normal free serum cortisol levels. The only biochemical feature to distinguish the symptomatic subject was increased cortisol pulsatility, and we suggest that this may influence glucocorticoid signaling and contribute to symptoms previously associated with CBG deficiency.