Lessons from KEEPS: the Kronos Early Estrogen Prevention Study.

The Kronos Early Estrogen Prevention Study (KEEPS) was a randomized, double-blind, placebo-controlled trial designed to determine the effects of hormone treatments (menopausal hormone treatments [MHTs]) on the progression of carotid intima-medial thickness (CIMT) in recently menopausal women. Participants less than 3 years from menopause and without a history of overt cardiovascular disease (CVD), defined as no clinical CVD events and coronary artery calcium < 50 Agatston units, received either oral conjugated equine estrogens (0.45 mg/day) or transdermal 17ß-estradiol (50 µg/day), both with progesterone (200 mg/day for 12 days/month), or placebo pills and patches for 4 years. Although MHT did not decrease the age-related increase in CIMT, KEEPS provided other important insights about MHT effects. Both MHTs versus placebo reduced the severity of menopausal symptoms and maintained bone density, but differed in efficacy regarding mood/anxiety, sleep, sexual function, and deposition of ß-amyloid in the brain. Additionally, genetic variants in enzymes for metabolism and uptake of estrogen affected the efficacy of MHT for some aspects of symptom relief. KEEPS provides important information for use of MHT in clinical practice, including type, dose, and mode of delivery of MHT recently after menopause, and how genetic variants in hormone metabolism may affect MHT efficacy on specific outcomes.

Cerebrovascular reactivity after cessation of menopausal hormone treatment.

OBJECTIVE: Women who are currently using menopausal hormone therapy (MHT) have higher cerebrovascular reactivity when compared with postmenopausal women who are not taking MHT; however, the effect of cessation of MHT on cerebrovascular reactivity is not known. Given that MHT can have structural and activational effects on vascular function, this study was performed to characterize cerebrovascular reactivity following cessation of MHT in women at low risk for cerebrovascular disease. METHODS: Cerebrovascular reactivity was measured in a subset of women from the Kronos Early Estrogen Prevention Study (KEEPS) 3 years after cessation of the study drug (oral conjugated equine estrogen, transdermal 17ß-estradiol, or placebo [PLA]). RESULTS: Age, body mass index, and blood pressure were comparable among groups. At rest, the middle cerebral artery velocity (MCAv), cerebrovascular conductance index, mean arterial pressure, and cerebral pulsatility index did not differ among groups. Slope-based summary measures of cerebrovascular reactivity did not differ significantly among groups. However, utilizing repeated-measures modeling, there was a significant upward shift in MCAv responses (p = 0.029) in the combined MHT group compared with the PLA group. CONCLUSION: MHT has a marginal sustained effect on cerebrovascular reactivity when measured 3 years after cessation of hormone treatment.

Pregnancy history, coronary artery calcification and bone mineral density in menopausal women.

OBJECTIVE: This study examined relationships, by pregnancy histories, between bone mineral density (BMD) and coronary artery calcification (CAC) in postmenopausal women. METHODS: Forty women identified from their medical record as having pre-eclampsia (PE) were age/parity-matched with 40 women having a normotensive pregnancy (NP). Vertebral (T4-9) BMD and CAC were assessed by quantitative computed tomography in 73 (37 with PE and 36 with NP) of the 80 women. Analyses included linear regression using generalized estimating equations. RESULTS: Women averaged 59 years of age and 35 years from the index pregnancy. There were no significant differences in cortical, trabecular or central BMD between groups. CAC was significantly greater in the PE group (p = 0.026). In multivariable analysis, CAC was positively associated with cortical BMD (p = 0.001) and negatively associated with central BMD (p = 0.036). There was a borderline difference in the association between CAC and central BMD by pregnancy history (interaction, p = 0.057). CONCLUSIONS: Although CAC was greater in women with a history of PE, vertebral BMD did not differ between groups. However, both cortical and central BMD were associated with CAC. The central BMD association was marginally different by pregnancy history, suggesting perhaps differences in underlying mechanisms of soft tissue calcification.

Differential effects of hormone therapy on serotonin, vascular function and mood in the KEEPS.

BACKGROUND: Serotonin (5-hydroxytryptamine, 5-HT) is modulated by sex steroid hormones and affects vascular function and mood. In the Kronos Early Estrogen Prevention Cognitive and Affective Ancillary Study (KEEPS-Cog), women randomized to oral conjugated equine estrogens (oCEE) showed greater benefit on affective mood states than women randomized to transdermal 17ß-estradiol (tE2) or placebo (PL). This study examined the effect of these treatments on the platelet content of 5-HT as a surrogate measure of 5-HT synthesis and uptake in the brain. METHODS: The following were measured in a subset (n = 79) of women enrolled in KEEPS-Cog: 5-HT by ELISA, carotid intima-medial thickness (CIMT) by ultrasound, endothelial function by reactive hyperemic index (RHI), and self-reported symptoms of affective mood states by the Profile of Mood States (POMS) questionnaire. RESULTS: Mean platelet content of 5-HT increased by 107.0%, 84.5% and 39.8%, in tE2, oCEE and PL groups, respectively. Platelet 5-HT positively correlated with estrone in the oCEE group and with 17ß- estradiol in the tE2 group. Platelet 5-HT showed a positive association with RHI, but not CIMT, in the PL and oCEE groups. Reduction in mood scores for depression-dejection and anger-hostility was associated with elevations in platelet 5-HT only in the oCEE group (r = -0.5, p = 0.02). CONCLUSIONS: Effects of oCEE compared to tE2 on RHI and mood may be related to mechanisms involving platelet, and perhaps neuronal, uptake and release of 5-HT and reflect conversion of estrone to bioavailable 17ß-estradiol in platelets and the brain.

Endothelial function in women of the Kronos Early Estrogen Prevention Study.

OBJECTIVE: Endothelial dysfunction occurs early in the atherosclerotic disease process, often preceding clinical symptoms. Use of menopausal hormone treatment (MHT) to reduce cardiovascular risk is controversial. This study evaluated effects of 4 years of MHT on endothelial function in healthy, recently menopausal women. METHODS: Endothelial function was determined by pulse volume digital tonometry providing a reactive hyperemia index (RHI) in a subset of women enrolled in the Kronos Early Estrogen Prevention Study. RHI was measured before and annually after randomization to daily oral conjugated equine estrogen (oCEE, 0.45 mg), weekly transdermal 17ß-estradiol (tE2, 50 µg) each with intermittent progesterone (200 mg daily 12 days of the month) or placebo pills and patch. RESULTS: At baseline, RHI averaged 2.39 ± 0.69 (mean ± standard deviation; n = 83), and over follow-up did not differ significantly among groups: oCEE, 2.26 ± 0.48 (n = 26); tE2, 2.26 ± 0.45 (n = 24); and placebo, 2.37 ± 0.37 (n = 33). Changes in RHI did not correlate with changes in traditional cardiovascular risk factors, but may inversely correlate with carotid intima medial thickness (Spearman correlation coefficient ρ = -0.268, p = 0.012). CONCLUSION: In this 4-year prospective assessment of recently menopausal women, MHT did not significantly alter RHI when compared to placebo.

Analytical evidence of heterogeneous lead accumulation in the hypothalamic defence area and nucleus tractus solitarius.

Lead is a potent toxicant associated with adverse cardiovascular effects and hypertension in children. Yet, few studies have determined if autonomic dysfunction associated with lead exposure involves brain regions which regulate autonomic responses. Central autonomic nuclei such as the nucleus tractus solitarius (NTS) and hypothalamic defence area (HDA) may be particularly sensitive to lead infiltration because they are adjacent to ventricles and areas with semi-permeable blood-brain-barriers. To understand if autonomic nuclei are sensitive to lead accumulation Wistar rats were exposed to lead from the gestational period and lead levels were quantified in brain regions that regulate arterial pressure: the NTS and the HDA. Energy dispersive X-ray fluorescence (EDXRF) was used to quantify total brain lead levels and revealed no differences between exposed and control tissues; measured values were close to the detection limit (2µg/g). Electrothermal atomic absorption spectrometry (ETAAS) was also used, which has a greater sensitivity, to quantify lead. There was ∼2.1µg/g lead in the NTS and ∼3.1µg/g lead in the HDA of exposed rats, and no lead in the control rats. There were greater lead levels in the HDA (∼50%) as compared with the NTS. Pathology studies revealed more prominent lead granules in the HDA as compared with the NTS. Increased microglia and astrocyte activation was also noted in the NTS of lead exposed rats as compared with the HDA. Regional differences in neuro-inflammatory responses likely contribute to heterogeneous lead accumulation, with enhanced clearance of lead in the NTS. Future studies will resolve the mechanisms underpinning tissue-specific lead accumulation.

Gestational flu exposure induces changes in neurochemicals, affiliative hormones and brainstem inflammation, in addition to autism-like behaviors in mice.

The prevalence of neurodevelopmental disorders such as autism is increasing, however the etiology of these disorders is unclear and thought to involve a combination of genetic, environmental and immune factors. A recent epidemiological study found that gestational viral exposure during the first trimester increases risk of autism in offspring by twofold. In mice gestational viral exposures alter behavior of offspring, but the biological mechanisms which underpin these behavioral changes are unclear. We hypothesized that gestational viral exposure induces changes in affiliative hormones, brainstem autonomic nuclei and neurotransmitters which are associated with behavioral alterations in offspring. To address this hypothesis, we exposed pregnant mice to influenza A virus (H3N2) on gestational day 9 and determined behavioral, hormonal and brainstem changes in male and female offspring. We found that gestational flu exposure induced dose-dependent alterations in social and aggressive behaviors (p≤0.05) in male and female offspring and increases in locomotor behaviors particularly in male offspring (p≤0.05). We found that flu exposure was also associated with reductions in oxytocin and serotonin (p≤0.05) levels in male and female offspring and sex-specific changes in dopamine metabolism. In addition we found changes in catecholaminergic and microglia density in brainstem tissues of male flu exposed offspring only (p≤0.05). This study demonstrates that gestational viral exposure induces behavioral changes in mice, which are associated with alterations in affiliative hormones. In addition we found sex-specific changes in locomotor behavior, which may be associated with sex-specific alterations in dopamine metabolism and brainstem inflammation. Further investigations into maternal immune responses are necessary to unravel the molecular mechanisms which underpin abnormal hormonal, immune and behavioral responses in offspring after gestational viral exposure.

Novel inter-hemispheric white matter connectivity in the BTBR mouse model of autism.

Alterations in the volume, density, connectivity and functional activation of white matter tracts are reported in some individuals with autism and may contribute to their abnormal behaviors. The BTBR (BTBR T+tf/J) inbred strain of mouse, is used to model facets of autism because they develop low social behaviors, stereotypical and immune changes similar to those found in people with autism. Previously, it was thought a total absence of corpus callosal interhemispheric connective tissues in the BTBR mice may underlie their abnormal behaviors. However, postnatal lesions of the corpus callosum do not precipitate social behavioral problems in other strains of mice suggesting a flaw in this theory. In this study we used digital pathological methods to compare subcortical white matter connective tracts in the BTBR strain of mice with those found in the C57Bl/6 mouse and those reported in a standardized mouse brain atlas. We report, for the first time, a novel connective subcortical interhemispheric bridge of tissue in the posterior, but not anterior, cerebrum of the BTBR mouse. These novel connective tissues are comprised of myelinated fibers, with reduced myelin basic protein levels (MBP) compared to levels in the C57Bl/6 mouse. We used electrophysiological analysis and found increased inter-hemispheric connectivity in the posterior hemispheres of the BTBR strain compared with the anterior hemispheres. The conduction velocity was slower than that reported in normal mice. This study shows there is novel abnormal interhemispheric connectivity in the BTBR strain of mice, which may contribute to their behavioral abnormalities.

Comparison of calibrated and uncalibrated bone mineral density by CT to DEXA in menopausal women.

OBJECTIVES: Coronary artery disease and osteoporosis increase in women after menopause. Computed tomography (CT) scans of the heart used to evaluate coronary arterial calcification include images of the thoracic vertebrae. The utility of using these images to assess bone health in women remains to be defined. Analyses of thoracic spine volumetric bone mineral density (vBMD) from CT scans of the heart were performed to determine how specific calibration affects the ability to assess vBMD in recently menopausal women and to evaluate how vBMD relates to areal bone mineral density (aBMD) using dual-energy X-ray absorptiometry (DEXA). METHODS: Women (n = 111) enrolled in the Kronos Early Estrogen Prevention Study (KEEPS) at Mayo Clinic underwent a CT scan of the heart that included calibration phantoms and a DEXA of the lumbar spine. The Spine Cancer Assessment program was used to determine vBMD of thoracic vertebrae with and without the calibration correction. RESULTS: Trabecular bone vBMD at T8 averaged 163.57±28.58 and 157.94±27.55 mg/cc (mean±standard deviation, SD) for calibrated and uncalibrated values, respectively. The relationship between calibrated and uncalibrated measures approached unity (R = 0.98). Lumbar spine (L2-4) aBMD was 1.19±0.16 g/cm(2) (mean±SD). Both calibrated and uncalibrated thoracic vBMD correlated positively and significantly with lumbar aBMD, but the relationship was less than unity (R = 0.63). CONCLUSION: Uncalibrated measures of thoracic spine vBMD obtained from CT scans of the heart may provide clinically relevant information about bone health and osteoporosis/osteopenia risk in recently menopausal women.

Coronary arterial calcification and thoracic spine mineral density in early menopause.

OBJECTIVES: Cardiovascular disease and osteoporosis increase in women after menopause. While aortic calcification is associated with bone loss in women, a similar relationship for coronary arterial calcification (CAC), a risk factor for coronary artery disease in women, is less clear. This study was designed to examine the relationship between CAC and volumetric bone mineral density (vBMD) in women (n=137) who were within a median of 18 months past their last menses at screening for the Kronos Early Estrogen Prevention Study (KEEPS). METHODS: CAC was measured using 64-slice computed tomography; vBMD was measured from these images using the Spine Cancer Assessment program. Concentrations of osteocalcin, bone alkaline phosphatase, tartrate-resident acid phosphatase-5b and osteopontin as bone matrix protein in serum and plasma were evaluated by ELISA. RESULTS: CAC scores ranged from 0 to 327.6 Agatston Units (AU); 113 women had a score of 0 AU, 20 had a CAC score between 0 and 50 AU, and four had a CAC score>50 AU. Although not statistically significant, there was a trend toward decreasing central density of thoracic T9 with increasing CAC. On average, levels of markers of bone turnover were within the normal range but did not correlate with age or with months past menopause. CONCLUSIONS: Clinically significant CAC and spine vBMD are quantifiable from the same scans within the first 3 years of menopause. Additional work is needed to determine how these measurements change with increasing age or with estrogenic treatments.

Sex, hormones and neuroeffector mechanisms.

Incidence and rate of cardiovascular disease differ between men and women across the life span. Although hypertension is more prominent in men than women, there is a group of vasomotor disorders [i.e. Raynaud's disease, postural orthostatic tachycardia syndrome and vasomotor symptoms (hot flashes) of menopause and migraine] with a female predominance. Both sex and hormones interact to modulate neuroeffector mechanisms including integrated regulation of the Sry gene and direct effect of sex steroid hormones on synthesis, release and disposition of monoamine neurotransmitters, and distribution and sensitivity of their receptors in brain areas associated with autonomic control. The interaction of the sex chromosomes and steroids also modulates these effector tissues, that is, the heart, vascular smooth muscle and endothelium. Although involvement of central serotonergic centres has been studied in regard to mood disorders such as depression, their contribution to cardiovascular risk is gaining attention. Studies are needed to further evaluate how hormonal treatments and drugs used to modulate adrenergic and serotonergic activity affect progression and risk for cardiovascular disease in men and women.

Sex-based differences in vascular function.

Cardiovascular disease is the leading cause of morbidity and mortality for both men and women in the USA. However, there are differences between the sexes in age-dependent onset, severity, symptoms and outcomes. Basic research into the causes of sex-dependent differences in cardiovascular disease is ongoing and includes investigation into genetic variation in expression and distribution of receptors for the sex steroids; specificity of natural and synthetic ligands that activate the sex steroid receptors; and intracellular mechanisms that are activated by the receptors in all components of the vessel wall and blood elements, which integrate to regulate vascular tone, vascular repair and remodeling in health and disease. In this era of personalized medicine, basic research into mechanisms of sex differences in vascular function will result in improved prevention, detection and treatment of cardiovascular disease in both men and women.

Developmental PCB exposure induces hypothyroxinemia and sex-specific effects on cerebellum glial protein levels in rats.

Polychlorinated biphenyls (PCBs) are persistent lipophilic environmental contaminants which are found in fatty tissues of humans and wild-life alike. Maternal transfer of PCBs to offspring is easily achieved across the placenta and via lactation. In male rats, perinatal PCB exposure induces behavioral abnormalities, in addition to hypothyroxinemia and white matter changes. There are sex differences in white matter volume synthesis and density in adult and aged rodents. Yet whether PCB exposure effects on white matter are sex-specific is unclear, because the previous studies were conducted in male offspring. Furthermore, although hypothyroxinemia induced by PCB exposure is thought to trigger white matter changes, PCBs also affect interleukin-6 (IL-6) expression, and IL-6 regulates white matter growth. We hypothesized that perinatal PCB exposure would have sex-specific effects on white matter development associated with altered IL-6 levels. We found that female offspring had higher levels of myelin basic protein (MBP) than males did, at postnatal day (PND) 7, 18 and 21. PCB exposure induced hypothyroxinemia in males and females at PND7, 14, 21, and 42. PCB exposure also increased MBP and reduced glial fibrillary acidic protein (GFAP) levels in males at PND21, but had the opposite effect in females. In addition, at PND14 and 21, PCB exposure elevated IL-6 levels in male offspring only. The induction of sex-specific changes in white matter proteins, in the absence of sex differences in thyroxine levels after PCB exposure, suggests that serum thyroxine levels do not directly contribute to the white matter alterations. Instead, IL-6 may contribute to increased MBP levels in males, whereas in females estromimetic and thyromimetic PCB metabolites may affect white matter development. This data adds to an increasing body of literature showing that perinatal insults induce sex-specific effects in offspring.

Sex effects of interleukin-6 deficiency on neuroinflammation in aged C57Bl/6 mice.

High levels of Interleukin-6 (IL-6) are associated with an increased risk of dementia in the elderly and can increase neuroinflammation in mice. Dementia is more frequent in females, and IL-6 is regulated by estrogen, suggesting that elevated IL-6 levels may contribute to neuroinflammation and dementia particularly in women. Therefore we hypothesized that IL-6 deficient ((-/-)) female mice would have lower aging-related neuroinflammation than wild type (WT). We quantified neuroinflammatory markers which are affected by aging, and regulated by both estrogen and IL-6; glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), interferon gamma (IFNgamma), lipid peroxidation (MDA), and synaptic density (SNAP25) and in IL-6(-/-) and WT C57Bl/6 mice. To determine age effects we used mid-age (18months) and old-age (24months) mice, and to determine region specific effects we used the hippocampus which is impaired in dementia and the cerebellum which is unimpaired in dementia. Unexpectedly, there were no effects of IL-6 deficiency on GFAP, MDA or SNAP25 levels in females, but IL-6 deficiency was associated with lower cerebellar MBP (p<0.05) levels. Interestingly, the old-aged IL-6(-/-) males had higher GFAP and MDA levels (p<0.05) in both the hippocampus and cerebellum, in addition to a greater body weight than WT. We suggest that IL-6 is important for promoting myelin synthesis in aged females, and that drugs which inhibit the synthesis of IL-6 in males may inadvertently affect fatty acid metabolism and augment aging-related neuroinflammation.

Endothelial function and cardiovascular risk stratification in menopausal women.

BACKGROUND: Peripheral arterial, endothelium-dependent, flow-mediated reactive hyperemia is reduced in individuals with atherosclerosis. This study tested the hypothesis that digital tonometry, as a surrogate of endothelial function, is useful to stratify cardiovascular risk in recently menopausal women who are asymptomatic for cardiovascular disease. METHODS: Women undergoing screening for the Kronos Early Estrogen Prevention Study (KEEPS) were evaluated for conventional risk factors, flow-mediated reactive hyperemia by digital tonometry (RHI), carotid intima-media thickness (CIMT) by ultrasound, and coronary arterial calcium (CAC) by 64-slice CT scanner. RESULTS: One hundred and two non-diabetic Caucasian women (53.0 +/- 2.3 years old, 18.0 +/- 9.0 months past their last menses) participated; 72% were never-smokers. Fourteen women had positive CAC scores (range 0.5-133 Agatston units); CIMT ranged from 0.57 to 1.06 mm. RHI ranged from 1.26 to 5.44. RHI did not correlate with time past menopause, CAC, CIMT, total cholesterol or low density lipoprotein cholesterol. The significant negative correlation of RHI with body mass index (r = -0.21, p = 0.031) was lost in non-smokers (r = - 0.17, p = 0.14). There was also a negative correlation of high density lipoprotein cholesterol with CAC, both in the overall group and non-smokers (rho = -0.20, p = 0.05 and rho = -0.27, p = 0.02, respectively). CONCLUSIONS: RHI varies widely in healthy women within the first 3 years of menopause. RHI was not associated with standard risk assessment algorithms, CAC or CIMT. RHI may indicate an additional, independent component and non-invasive tool to further stratify cardiovascular risk in recently menopausal women. As KEEPS continues, data on RHI will provide information regarding hormonal therapy, endovascular biology and atherosclerotic risk.

Using basic science to design a clinical trial: baseline characteristics of women enrolled in the Kronos Early Estrogen Prevention Study (KEEPS).

Observational and epidemiological studies suggest that menopausal hormone therapy (MHT) reduces cardiovascular disease (CVD) risk. However, results from prospective trials showed neutral or adverse effects most likely due to differences in participant demographics, such as age, timing of initiation of treatment, and preexisting cardiovascular disease, which reflected in part the lack of basic science information on mechanisms of action of hormones on the vasculature at the time clinical trials were designed. The Kronos Early Estrogen Replacement Study (KEEPS) is a prospective, randomized, controlled trial designed, using findings from basic science studies, to test the hypothesis that MHT when initiated early in menopause reduces progression of atherosclerosis. KEEPS participants are younger, healthier, and within 3 years of menopause thus matching more closely demographics of women in prior observational and epidemiological studies than women in the Women's Health Initiative hormone trials. KEEPS will provide information relevant to the critical timing hypothesis for MHT use in reducing risk for CVD.

Reduced glutathione is highly expressed in white matter and neurons in the unperturbed mouse brain--implications for oxidative stress associated with neurodegeneration.

Oxidative stress is implicated in the pathogenesis of many neurodegenerative diseases, including Parkinson's disease and Alzheimer's disease. The depletion of glutathione (GSH) a powerful antioxidant renders cells particularly vulnerable to oxidative stress. Isolated neuronal and glial cell culture studies suggest that glia rather than neurons have greatest reserves of GSH, implying that neurons are most sensitive to oxidative stress. However, pathological in vivo studies suggest that GSH associated enzymes are elevated in neurons rather than astrocytes. The active, reduced form of GSH is rapidly degraded thus making it difficult to identify the location of GSH in post-mortem tissue. Therefore, to determine whether GSH is more highly expressed in neurons or astrocytes we perfused mouse brains with a solution containing NEM which reacts with the sulfhydryl group of GSH, thus locking the active form in situ, prior to immunostaining with an anti-GS-NEM antibody. We obtained brightfield and fluorescent digital images of sections stained with DAPI and antibodies directed against GS-NEM, glial fibrillary acidic protein (GFAP) in regions containing the hippocampus, striatum, frontal cortex, midbrain nuclei, cerebellum and reticular formation neurons. GSH was most abundant in neurons and white matter in all brain regions, and only in occasional astrocytes lining the third and fourth ventricles. High levels of GSH in neurons and white matter, suggests astrocytes rather than neurons may be particularly vulnerable to oxidative stress.

Do calcifying nanoparticles promote nephrolithiasis? A review of the evidence.

Although much has been learned regarding the pathogenesis of kidney stones, the reason(s) why some individuals form stones while others do not remains incompletely understood. Nanoparticles, which have been observed in geologic samples, have also been isolated from biologic specimens, including kidney stones. These nanoparticles have certain properties that are consistent with a novel life form, including in vitro self-replication, and contain lipids, DNA and proteins. Therefore, it has been hypothesized that nanoparticles may represent a type of infective agent that initiates stone formation in some individuals. Despite a large body of intriguing and suggestive evidence, the true biologic nature of these entities has been elusive, and controversy remains as to whether these nano-sized particles are analogous to other recently described unusual and novel microorganisms, or a transmissible, yet inert nanoparticle. Although unique DNA or RNA has yet to be identified, a proteomic biosignature is beginning to emerge that may allow more definitive clinical investigation. This review evaluates the current evidence regarding nanoparticles as causal to disease and emphasizes the need for additional research to further elucidate their role in human stone formation.

Circulating microparticles and endogenous estrogen in newly menopausal women.

BACKGROUND: Estrogen modulates antithrombotic characteristics of the vascular endothelium and the interaction of blood elements with the vascular surface. A marker of these modulatory activities is formation of cell-specific microparticles. This study examined the relationship between blood-borne microparticles and endogenous estrogen at menopause. METHODS: Platelet activation and plasma microparticles were characterized from women being screened (n = 146) for the Kronos Early Estrogen Prevention Study. Women were grouped according to serum estrogen (< 20 pg/ml; low estrogen, n = 21 or > 40 pg/ml; high estrogen, n = 11). RESULTS: Age, body mass index, blood pressure and blood chemistries were the same in both groups. No woman was hypertensive, diabetic or a current smoker. Platelet counts, basal and activated expression of P-selectin on platelet membranes were the same, but activated expression of glycoprotein IIb/IIIa was greater in the high-estrogen group. Numbers of endothelium-, platelet-, monocyte- and granulocyte-derived microparticles were greater in the low-estrogen group. Of the total numbers of microparticles, those positive for phosphatidylserine and tissue factor were also greater in the low-estrogen group. CONCLUSION: These results suggest that, with declines in endogenous estrogen at menopause, numbers of procoagulant microparticles increase and thus may provide a means to explore mechanisms for cardiovascular risk development in newly menopausal women.

Medullary autonomic pathology in carotid sinus hypersensitivity.

AIMS: Carotid sinus hypersensitivity (CSH) is an ageing-related autonomic disorder, rarely occurring before the age of 50 years but increasing in incidence thereafter. Clinical symptoms of CSH include falls and dizziness, thought to be precipitated by dysfunctional baroreflex responses. CSH is highly prevalent in Alzheimer's disease (AD), Parkinson's disease (PD) and dementia with Lewy bodies (DLB); diseases that are associated with variable degeneration of medullary autonomic nuclei which regulate baroreflex responses. Currently, there are no descriptions of the integrity of medullary autonomic nuclei in CSH. We hypothesized medullary autonomic degeneration is found in elderly patients with CSH. METHODS: Using in vitro digital imaging, we quantified the burden of tau, amyloid beta and alpha-synuclein in autonomic nuclei of 12 patients prospectively assessed with CSH (age 83 years) compared with 14 (80 years) control subjects. RESULTS: We found increased tau (P < 0.000) accumulation in baroreflex associated nuclei, but not the hypoglossal or raphe in the CSH patients. Medullary tau accumulation was not related to the development of AD in the CSH patients. Tau was colocalized to catecholaminergic neurones and occurred in the absence of neuronal loss. We found no difference in alpha-synuclein, amyloid beta or microglial numbers between the CSH cases and controls. CONCLUSIONS: We suggest that hyperphosphorylated tau accumulation particularly in tyrosine hydroxylase containing neurones may impair central regulation of baroreflex responses in patients with CSH. Future clinic-pathological investigations should reveal whether medullary degeneration is the cause of CSH symptoms.