Early Morning Increase Research Articles

EARLY MORNING HEMODYNAMIC CHANGES AND LEFT VENTRICULAR HYPERTROPHY AND MORTALITY IN HEMODIALYSIS PATIENTS

Objective: Amplified early morning increase in BP, a phenomenon accompanied by a parallel rise in heart rate (HR), is a marker of high cardiovascular risk in the general population. The early morning changes in these parameters have not been investigated in the hemodialysis population. Design and method: In a pilot, single center, study including a series of 58 hemodialysis patients we measured the pre-awakening BP and HR surges and the nocturnal dipping of the same parameters as well as other established indicators of autonomic function (weighted 24h systolic BP and HR variability) and tested their relationship with the left ventricular mass index (LVMI) and with the risk of death over a median follow up of 40 months. Results: The pre-awakening HR surge (r = -0.46, P = 0.001) was inversely associated with LVMI and the risk of death [HR (1 unit): 0.89, 95% CI: 0.83-0.96, P = 0.001] while the corresponding BP surge largely failed to associate with these outcomes. The link between the pre-awakening HR surge with LVMI and death was robust and largely independent of established risk factors in the hemodialysis population, including the nocturnal dipping of BP. Weighted 24h systolic BP and HR variability did not correlate with LVMI (all P>0.11) nor with the risk of death (P>0.11) and these parameters were also independent of the nocturnal dipping of systolic BP and HR. Conclusions: This pilot study suggests that the low early morning changes in HR, likely reflecting enhanced sympathetic activity, entail a high risk for LVH and mortality in the hemodialysis population.

EARLY MORNING HEMODYNAMIC CHANGES AND LEFT VENTRICULAR HYPERTROPHY AND MORTALITY IN HEMODIALYSIS PATIENTS

Objective: An exaggeration of the early morning increase in BP, a phenomenon accompanied by a parallel rise in heart rate (HR), is a marker of high cardiovascular risk. The early morning changes in these parameters have not been investigated in the hemodialysis population. Design and method: In a pilot, single center, study including a series of 58 patients we measured the pre-awakening BP and HR surges and the nocturnal dipping of the same parameters as well as other established indicators of autonomic function (weighted 24 h systolic BP and HR variability) and tested their relationship with the left ventricular mass index (LVMI) and with the risk of death over a median follow up of 40 months. Results: The pre-awakening HR surge (r = -0.46, P = 0.001) but not the corresponding BP surge (r = -0.1, P = 0.98) associated with LVMI and the risk of death [HR (1 unit): 0.89, 95% CI: 0.83–0.96, P = 0.001]. The link between the pre-awakening HR surge with these outcome measures was robust and largely independent of established risk factors in the hemodialysis population including the systolic BP dipping. Weighted 24 h systolic BP (SD) and HR (SD) variability did not correlate with LVMI (all P> 0.11) nor with the risk of death (P > 0.11). Overall, among markers of early morning hemodynamic changes and of hemodynamic variability, the pre-awakening HR surge was the strongest correlate of LVMI and a the strongest predictor of death. Conclusions: This pilot study suggests that low early morning changes in HR, a biomarker reflecting sympathetic activity, entail a high risk for LVH and mortality in the hemodialysis population.

MO858: Early Morning Haemodynamic Changes and Left Ventricular Hypertrophy and Mortality In Haemodialysis Patients

Abstract BACKGROUND AND AIMS Amplified early morning increase in BP, a phenomenon accompanied by a parallel rise in heart rate (HR), is a marker of high cardiovascular risk in the general population. The early morning changes in these parameters have not been investigated in the haemodialysis population. METHOD In a pilot, single centre, study including a series of 58 haemodialysis patients we measured the pre-awakening BP and HR surges and the nocturnal dipping of the same parameters as well as other established indicators of autonomic function (weighted 24h systolic BP and HR variability) and tested their relationship with the left ventricular mass index (LVMI) and with the risk of death over a median follow up of 40 months. RESULTS The pre-awakening HR surge (r = –0.46; P = 0.001) was inversely associated with LVMI and the risk of death [HR (1 unit): 0.89, 95% confidence interval: 0.83–0.96; P = 0.001] while the corresponding BP surge largely failed to associate with these outcomes. The link between the pre-awakening HR surge with LVMI and death was robust and largely independent of established risk factors in the haemodialysis population, including the nocturnal dipping of BP. Weighted 24 h systolic BP and HR variability did not correlate with LVMI (all P > 0.11) nor with the risk of death (P > 0.11) and these parameters were also independent of the nocturnal dipping of systolic BP and HR. CONCLUSION This pilot study suggests that the low early morning changes in HR, likely reflecting enhanced sympathetic activity, entail a high risk for LVH and mortality in the haemodialysis population.

Early morning hemodynamic changes and left ventricular hypertrophy and mortality in hemodialysis patients.

An exaggeration of the early morning increase in BP, a phenomenon accompanied by a parallel rise in heart rate (HR), is a marker of high cardiovascular risk. The early morning changes in these parameters have not been investigated in the hemodialysis population. In a pilot, single center study including a series of 58 patients we measured the pre-awakening BP and HR surges and the nocturnal dipping of the same parameters as well as other established indicators of autonomic function (weighted 24h systolic BP and HR variability) and tested their relationship with the left ventricular mass index (LVMI) and with the risk of death over a median follow up of 40months. The pre-awakening HR surge (r = -0.46, P = 0.001) but not the corresponding BP surge (r = -0.1, P = 0.98) was associated with LVMI and the risk of death [HR (1 unit): 0.89, 95% CI 0.83-0.96, P = 0.001]. The link between the pre-awakening HR surge with these outcome measures was robust and largely independent of established risk factors in the hemodialysis population, including the nocturnal dipping of BP. Weighted 24h systolic BP and HR variability did not correlate with LVMI (all P > 0.11) nor with the risk of death (P > 0.11) and were also independent of the nocturnal dipping of systolic BP and HR. This pilot study suggests that the low early morning changes in HR, likely reflecting enhanced sympathetic activity, entail a high risk for left ventricular hypertrophy (LVH) and mortality in the hemodialysis population.

Transient Variations of Total Electron Content (TEC) Over a Terrestrial Point within Magnetic Anomaly Region

This paper investigate the variability of Total Electron Content TEC over a terrestrial point within equatorial anomaly region using the NovAtel GSV 4000B GPS-SCINDA system at Akure (7.3°N, 5.2°E), Nigeria. This system is capable of tracking up to 14 GPS satellites simultaneously. Total Electron Content (TEC) over equatorial region using a real time data collected via a GPS-SCINDA facility were analyzed to study the ionospheric variations in terms of Total Electron Content (TEC) for the period of three years. Diurnal variations and Monthly mean variations of Total Electron Content within the equatorial anomaly region were examined. The diurnal variation of TEC showed pre-dawn minimum for a short period of time, followed by a steep early morning increase and then reached maximum value between 14:00 UT and 16:00 UT. The influence of solar activity on VTEC was investigated by taking the correlation coefficients between VTEC, F10.7cm radio flux index and sunspot numbers. The range of solar flux variation during the period of observation is very limited; there is high positive correlation (Correlation Coefficient 0.61) between daytime peak TEC and the solar F10.7 flux.

P1447EARLY MORNING ACCELERATION AND NOCTURNAL DECELERATION IN HEART RATE ASSOCIATE WITH LVH AND THE RISK OF DEATH AND CARDIOVASCULAR EVENTS IN HEMODIALYSIS PATIENTS

Abstract Background and Aims Cardiovascular deaths cluster in the early morning hours and studies in the general population documented that an exaggeration of the early morning increase in BP, a phenomenon accompanied by a parallel rise in heart rate (HR), is a marker of high cardiovascular risk. The circadian profile of BP and HR in hemodialysis patients is notoriously altered but the early morning changes in these parameters and the nocturnal profile of HR have not been investigated in this population. Method BP and HR were registered at 15 min intervals by ambulatory monitoring (24hABPM, Spacelab) during the day after hemodialysis in a series of 64 patients. We measured the early morning (the average of the 2 hours after awakening minus the average of the 2 hours pre-awakening) changes in BP and HR and the nocturnal decline in BP and HR and tested the relationship of these parameters with the left ventricular mass index (LVMI) and with the risk of all-cause and cardiovascular death over a median follow up of 40 months (Interquartile range 21-81) Results The rise in HR after awakening was strongly related in an inverse fashion with the LVMI (Spearman ρ=-0.61, P<001) suggesting that patients with a more pronounced increase in HR after awakening may be protected from LVH .Both, the decline in HR (ρ =-0.38, P=0.002) and in systolic BP (ρ =-0.31, P=0.01 ) during night-time associated inversely with LVMI. These associations remained significant also when they were reciprocally adjusted (P<0.01) in a model including also age, gender and simultaneous changes in BP. In contrast, the rise is systolic BP upon awakening had no relationship with the LVMI (ρ =0.18, P=0.18). Thirty-two deaths (16 cardiovascular) occurred during follow up. The early morning rise in HR was an inverse predictor of all cause death (HR=0.95; 95%CI 0.92-0.98 P=0.004 ) and of cardiovascular death (HR=0.95; 95%CI 0.91-0.98) in analyses adjusted for the simultaneous rise in systolic BP which per se failed to predict the same outcomes. Again, in similarity with analyses looking at LVMI, the nocturnal dipping in HR associated inversely with all cause and cardiovascular death (p=0.003). Conclusion The analysis of the nocturnal decline in HR and of the rise in HR increase upon awakening In hemodialysis patients reveals stronger links among these parameters and LVMI than the corresponding BP parameters. The protective effect on the left ventricle of a more pronounced HR rise upon awakening and of a more pronounced decline in HR during night time underscore the relevance of preserved autonomic function for cardiovascular protection in this population. These associations seem to go along with a reduced risk for all-cause and cardiovascular death. Analysis of the HR profile provides unique information for the risk of cardiomyopathy and cardiovascular events in the hemodialysis population.

First simultaneous measurements of peroxyacetyl nitrate (PAN) and ozone at Nam Co in the central Tibetan Plateau: impacts from the PBL evolution and transport processes

Abstract. Both peroxyacetyl nitrate (PAN) and ozone (O3) are key photochemical products in the atmosphere. Most of the previous in situ observations of both gases have been made in polluted regions and at low-altitude sites. Here we present the first simultaneous measurements of PAN and O3 at Nam Co (NMC; 30°46′ N, 90°57′ E, 4745 m a.s.l.), a remote site in the central Tibetan Plateau (TP). The observations were made during summer periods in 2011 and 2012. The PAN levels averaged 0.36 ppb (range: 0.11–0.76 ppb) and 0.44 ppb (range: 0.21–0.99 ppb) during 17–24 August 2011 and 15 May to 13 July 2012, respectively. The O3 level varied from 27.9 to 96.4 ppb, with an average of 60.0 ppb. Profound diurnal cycles of PAN and O3 were observed with minimum values around 05:00 LT, steep rises in the early morning, and broader platforms of high values during 09:00–20:00 LT. The evolution of the planetary boundary layer (PBL) played a key role in shaping the diurnal patterns of both gases, particularly the rapid increases of PAN and O3 in the early morning. Air entrainment from the free troposphere into the PBL seemed to cause the early-morning increase and be a key factor for sustaining the daytime high concentrations of both gases. The days with higher daytime PBL (about 3 km) showed stronger diurnal variations in both gases and were mainly distributed in the drier pre-monsoon period, while those with shallower daytime PBL (about 2 km) showed minor diurnal variations and were mainly distributed in the humid monsoon period. Episodes of higher PAN levels were occasionally observed at NMC. These PAN episodes were caused either by rapid downward transport of air masses from the middle/upper troposphere or by long-range transport of PAN plumes from north India, north Pakistan, and Nepal. The maximum PAN level in the downward transport cases ranged from 0.5 to 0.7 ppb. In the long-range transport case, the PAN level varied in the range of 0.3–1.0 ppb, with an average of 0.6 ppb. This long-range transport process influenced most of the western and central TP region for about a week in early June 2012. Our results suggest that polluted air masses from South Asia can significantly enhance the PAN level over the TP. As PAN acts as a reservoir of NOx, the impacts of pollution transport from South Asia on tropospheric photochemistry over the TP region deserve further studies.

Serum of obstructive sleep apnea patients impairs human coronary endothelial cell migration.

IntroductionEndothelial cell migration and proliferation play an important role in the growth and development of new blood vessels and endothelium healing. This process occurs in response to injury, inflammation and immune reactions. Dysfunction of the endothelium may play a significant role in development and progression of cardiovascular disease related to sleep-disordered breathing. The aim of our study was to evaluate the chemo-attractant activity of serum from obstructive sleep apnea (OSA) and normal subjects on coronary artery endothelial cell migration.Material and methodsWe studied 12 severe OSA patients, free of other co-morbidities and on no treatment, along with 12 age-, body mass index, and gender matched healthy controls. Blood was collected at three time points: at 21:00 before sleep, at 6:00 after waking from sleep, and at 11:00 (after 5 h of normal daytime activity). Serum chemo-attractant activity for human coronary endothelial cells was assessed using a colorimetric cell migration assay kit.ResultsIn healthy subjects, serum chemo-attractant activity peaked in the morning after waking from sleep (p = 0.02). This early morning increase was blunted in severe OSA subjects, in whom chemo-attractant activity was weaker than in normal controls (p = 0.02), and did not change significantly at the different time-points (p < 0.001 vs. controls).ConclusionsChemo-attractant activity of the serum from OSA patients is lower compared to serum from healthy subjects, especially in the morning. Altered chemo-attractant serum activity may conceivably contribute to the impairment of endothelial function in obstructive sleep apnea patients.

Daily Fasting Blood Glucose Rhythm in Male Mice: A Role of the Circadian Clock in the Liver.

Fasting blood glucose (FBG) and hepatic glucose production are regulated according to a circadian rhythm. An early morning increase in FBG levels, which is pronounced among diabetic patients, is known as the dawn phenomenon. Although the intracellular circadian clock generates various molecular rhythms, whether the hepatic clock is involved in FBG rhythm remains unclear. To address this issue, we investigated the effects of phase shift and disruption of the hepatic clock on the FBG rhythm. In both C57BL/6J and diabetic ob/ob mice, FBG exhibited significant daily rhythms with a peak at the beginning of the dark phase. Light-phase restricted feeding altered the phase of FBG rhythm mildly in C57BL/6J mice and greatly in ob/ob mice, in concert with the phase shifts of mRNA expression rhythms of the clock and glucose production-related genes in the liver. Moreover, the rhythmicity of FBG and Glut2 expression was not detected in liver-specific Bmal1-deficient mice. Furthermore, treatment with octreotide suppressed the plasma growth hormone concentration but did not affect the hepatic mRNA expression of the clock genes or the rise in FBG during the latter half of the resting phase in C57BL/6J mice. These results suggest that the hepatic circadian clock plays a critical role in regulating the daily FBG rhythm, including the dawn phenomenon.

The Effectiveness and Risks of Programming an Insulin Pump to Counteract the Dawn Phenomenon in Type 1 Diabetes.

Continuous subcutaneous insulin infusion (CSII) programming for an early morning increase in insulin delivery is frequently recommended to counteract the rise in glucose prior to breakfast (dawn phenomenon). However, both the effectiveness and safety of this approach have not been tested in the ambulatory setting. Using continuous glucose monitoring, we investigated the safety and effectiveness of early morning CSII programming for management of the dawn phenomenon in subjects with type 1 diabetes. We conducted a controlled, observational eight-month longitudinal study of type 1 diabetic patients (n=40). Reproducibility of the dawn phenomenon was determined in subjects treated with multiple daily injections of insulin (MDI, n=12) and those on CSII who did not program an early morning increase in insulin delivery (CSII non-programmers, n=8). The effects of early morning CSII programming were determined by comparing rates of the dawn phenomenon and hypoglycemia in CSII non-programmers versus CSII-users who programmed an early morning increase in insulin delivery (CSII programmers, n=20). The dawn phenomenon occurred in all tested subjects to a variable extent (median rate 56% of nights). CSII programming was not associated with a reduction in the occurrence of the dawn phenomenon (42%) compared to non-programmers (48%) (P=0.47) nor in the magnitude of the dawn phenomenon. Hypoglycemia occurred more frequently in the CSII programmers (37%) compared to non-programmers (18%) (P=0.001). The dawn phenomenon occurs unpredictably; therefore, early morning CSII programming for a fixed increase in early morning insulin delivery is ineffective and may be hazardous to the patient.

Non-dipping blood pressure profile in treated hypertensive patients

Aims: With the progressive increase of the clinical application of ambulatory blood pressure monitoring (ABPM) we started to understand the circadian variation of blood pressure which usually is characterized by a period of low values during sleep, an early-morning increase in pressures, and a plateau period while the individual is awake and active. Clinical studies with 24-h ABPM have shown that some cardiovascular complications and target organ damage tend to be more frequent in patients whose 24-h blood pressure profile is flattened (non-dippers).

Diurnal and seasonal variation of mercury species at coastal-suburban, urban, and rural sites in the southeastern United States

Observations for the 2005–2008 time period from three Southeastern Aerosol Research and Characterization (SEARCH) air quality monitoring sites are examined for diurnal and seasonal variation in concentrations of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particle bound mercury (HgP < 2.5 μm). The sites are located at 1) a suburban-coastal location near Pensacola, Florida (OLF), 2) an urban location in Birmingham, Alabama (BHM), and 3) a rural location west-northwest of Atlanta, Georgia (YRK). Average concentrations of GEM at both OLF and YRK are 1.35 ng m−3, whereas at BHM it is 2.12 ng m−3. All sites show increase in GEM concentration during the morning hours (0.023 and 0.011 ng m−3hr−1 at OLF and YRK between 6 and 10 AM, 0.038 ng m−3hr−1 at BHM between 5 and 10 AM) due to downward mixing of higher concentrations from the residual layer, after which OLF and YRK show negligible variation compared to decrease in concentration at BHM (2.3–1.9 ng m−3 from 10 AM to 6 PM). All sites show seasonal variation of GEM with enhanced concentrations found in winter and spring. Average GOM concentrations are 4.26, 8.55, and 78.2 pg m−3 at OLF, YRK, and BHM, respectively. Seasonally, GOM values are enhanced during fall and spring. All sites undergo a sinusoidal daytime variation of GOM that peaks in the afternoon, while BHM additionally exhibits an early morning enhancement likely caused by vertical mixing. The average HgP concentrations at OLF, YRK, and BHM are 2.49, 4.43, and 39.5 pg m−3, respectively. At OLF, vertical mixing causes an early morning increase in HgP concentration followed by an afternoon decline during all seasons. A daytime increase in HgP is found at YRK for all seasons, while at BHM, nocturnal accumulation followed by a daytime decline is also found for most seasons except winter. In winter, concentrations increase due to vertical mixing in the morning and then decline as the boundary layer grows. Boundary layer processes appear to play an important role in the seasonal and diurnal variation of Hg species and further investigation utilizing a boundary layer process model is warranted.

Targeting the time of day for glucocorticoid delivery in rheumatoid arthritis

Glucocorticoid treatment for rheumatoid arthritis is generally taken in the mornings, and there is some evidence to support this practice. However, increased understanding of the role of cytokines in the pathogenesis of rheumatoid arthritis, and of their interaction with the hypothalamic–pituitary–adrenal axis, has suggested that glucocorticoids delivered in the early hours of the morning may have additional efficacy. The development of appropriate tablet technology and the conduct of randomized controlled trials and detailed clinical studies have shown that the early morning increase in plasma IL-6 concentrations, and its associated diurnal increase in symptoms such as morning stiffness can both be reduced by nocturnal glucocorticoid treatment. Fears that hypothalamic–pituitary–adrenal axis responses might be further blunted appear to be unfounded.

Is ambulatory blood pressure monitoring finally catching on?

Evaluation of blood pressure (BP) using ambulatory BP monitoring (ABPM) may play an important role in predicting cardiovascular (CV) prognosis and is increasingly being used in clinical practice. ABPM may be particularly useful in assessing BP in patients with discrepancies between office and home BP readings in both patients with white coat hypertension and masked hypertension, in patients with labile hypertension to establish nondipper status, in patients with resistant hypertension and episodic hypotension, and to determine BP control in patients taking multiple medications with early morning surges in BP. ABPM is considered the gold standard in BP measurement and is also increasingly being used to verify BP in large clinical trials. ABPM provides information about BP during daily activities and during sleep. Nighttime BP measured by ABPM is superior to office BP measurement in predicting CV events. BP has a reproducible circadian profile with higher values while awake and active and lower values during rest and sleep and an early morning increase for 3 hours during a transition of sleep to wakefulness. In most people, BP drops by 10% to 20% during the night (nighttime dipping). Those without nighttime dipping appear to be at higher risk of CV disease. Recent studies have drawn attention to the potential importance of controlling not only daytime but also nighttime BP. In this regard, control of the early morning surge may prove to be particularly important in preventing stroke. ABPM is performed by using a device that is easily worn by the patient for 24 to 48 hours, and BP is usually measured every 15 to 20 minutes during the day and every 30 to 60 minutes at night. Patients also record an activity log, which can be correlated with BP changes. These BPs are recorded on the device and the average daytime (awake) or nighttime (sleep) BPs are determined from the data by a computer program. The percentage of BP readings exceeding the upper limit of normal reflects vascular ‘‘load’’ and is considered to provide a more quantifiable measure of systolic and diastolic BP effect than an individual BP measurement. Dipping status is determined by a 10% fall in systolic and diastolic BP comparing daytime with nighttime (and nap time) readings. The diagnosis of hypertension using ABPM depends on the time span over which it is interpreted. The following readings are defined as hypertension on ABPM: a 24-hour average BP >135 ⁄85 mm Hg, a daytime (awake) average BP >140 ⁄90 mm Hg, and a nighttime (asleep) average BP >125 ⁄ 75 mm Hg. ABPM continues to sharpen the relationship between BP profile and CV risk, and this is demonstrated in a report from the International Database of Ambulatory Blood Pressure Monitoring in Relation to Cardiovascular Outcomes (IDACO). This report provides some useful ‘‘side by side’’ comparisons of ambulatory BP measurements and office BP From the Department of Medicine, Hypertension Program, University of Pennsylvania School of Medicine, Philadelphia, PA Address for correspondence: Debbie L. Cohen, MD, Renal Division, University of Pennsylvania School of Medicine, 210 White Building, Philadelphia, PA 19104 E-mail: cohendl@mail.med.upenn.edu

Commentary: Revisiting the Early Morning Blood Pressure Surge and Myocardial Ischemia

In this issue of the Journal, Uen and colleagues’ article entitled ‘‘Early Morning Surge and Dipping Status of Blood Pressure: Are These of Predictive Value for Silent Myocardial Ischemia?’’ revisits the entity of circadian rhythms and coronary ischemia. In their study, the group evaluated 76 patients of 344 who demonstrated ST depression on 24-hour monitoring for ST-segment characteristics and blood pressure (BP). They determined that the degree of overnight BP dipping and concomitant early morning BP surge did not correlate with the presence of ST-segment depression indicative of myocardial ischemia. Notable within the data presented, but not specifically addressed by the authors in the discussion section, is the fact that in all of the time frames measured with the ambulatory BP monitoring system, the patients who did not demonstrate ST depression during the course of the day had statistically significantly lower mean systolic BP. Therefore, the most important fact to arise from these authors’ work is that overall BP control is more predictive of silent ischemia than either overnight BP dipping or early morning surges. The presence of a morning peak for acute myocardial infarction (MI) has been noted for decades but was disregarded from the earliest papers as being a reporting bias from patients sleeping through their symptoms. The Multicenter Investigation of Limitation of Infarct Size (MILIS) study demonstrated an increase in cardiac events during the hours of 6 am to 12 noon, utilizing time to peak creatinine kinase–MB fraction to determine the time of onset for the MI. A second study, the Intravenous Streptokinase in Acute Myocardial Infarction (ISAM) trial corroborated these results in more than 1700 patients, demonstrating a 4-fold greater likelihood of events between 8 am and 9 am compared with overnight hours. Similar patterns have emerged in patients presenting with sudden cardiac death (SCD) in several studies. There are several physiologic events demonstrating circadian rhythms that could account for the morning peak in acute ischemic cardiac events. There is an increase in sympathetic activity that accompanies and readies the body for awakening in the morning. Coincident with this is a rise in BP, pulse pressure, and heart rate, which may increase the hemodynamic stresses across the coronary arteries, most notably at the shoulder regions of the vulnerable plaques. Additionally, higher sympathetic tone may promote increased vascular tone and coronary vasoconstriction, while increasing metabolic demands on the myocardium. Furthermore, there is an early morning increase in platelet aggregability and a reduction in the fibrinolytic From the Cardiology Division, Department of Internal Medicine, University of Rochester Medical Center, Rochester, NY 14642 Address for correspondence: John D. Bisognano, MD, PhD, Cardiology Division, Department of Internal Medicine, University of Rochester, 601 Elmwood Avenue, Box 679-7, Rochester, NY 14642-8679 E-mail: john_bisognano@urmc.rochester.edu Manuscript received May 18, 2009; accepted May 22, 2009

Atmospheric mercury concentrations and speciation measured from 2004 to 2007 in Reno, Nevada, USA

Atmospheric elemental, reactive and particulate mercury (Hg) concentrations were measured north of downtown Reno, Nevada, USA from November 2004 to November 2007. Three-year mean and median concentrations for gaseous elemental Hg (Hg 0) were 1.6 and 1.5 ng m −3 (respectively), similar to global mean Hg 0 concentrations. The three-year mean reactive gaseous Hg (RGM) concentration (26 pg m −3) was higher than values reported for rural sites across the western United States. Well defined seasonal and daily patterns in Hg 0 and RGM concentrations were observed, with the highest Hg 0 concentrations measured in winter and early morning, and RGM concentrations being greatest in the summer and mid-afternoon. Elevated Hg 0 concentrations in winter were associated with periods of cold, stagnant air; while a regularly observed early morning increase in concentration was due to local source and surface emissions. The observed afternoon increase and high summer values of RGM can be explained by in situ oxidation of gaseous Hg 0 or mixing of RGM derived from the free troposphere to the surface. Because both of these processes are correlated with the same environmental conditions it is difficult to assess their overall contribution to the observed trends.

TEC variations during low solar activity period (2005–2007) near the Equatorial Ionospheric Anomaly Crest region in India

Abstract. The dual frequency signals from the GPS satellites recorded at Rajkot (22.29° N, 70.74° E, Geographic, 14.03° N Geomagnetic) near the Equatorial ionization anomaly crest in India have been analyzed to study the ionospheric variations in terms of Total Electron Content (TEC) for the low solar activity period from April 2005 to December 2007. In this study, we describe the diurnal and seasonal variations of TEC, solar activity dependence of TEC and effects of a space weather related event, a geomagnetic storm on TEC. The diurnal variation of TEC shows pre-dawn minimum for a short period of time, followed by a steep early morning increase and then reaches maximum value between 14:00 LT and 16:00 LT. The mean diurnal variations during different seasons are brought out. It is found that TEC at Rajkot is at its maximum during Equinoctial months (March, April, September, October), and minimum during the Winter months (November, December, January, February), with intermediate values during Summer months (May, June, July, August), showing a semi annual variation. TEC values have been decreasing since 2005, onwards showing positive correlation with solar activity. TEC variations during the geomagnetic storm commencing 24 August 2005 with Dst=−216 nT are analysed. TEC shows a positive ionospheric storm effect on the first day of the storm and negative ionospheric storm effect on the next day. The equatorial Electrojet control on the development of the equatorial anomaly is also demonstrated.

Characteristics of gender-related circadian arterial blood pressure in healthy adolescents

To define 24-h characteristics of arterial blood pressure in healthy adolescent girls and boys; to determine gender-related differences of blood pressure, its circadian pattern. The 24-h blood pressure was monitored hourly in healthy girls (n=22, without no account for the menstrual cycle phase) and boys (n=22). Additionally, blood pressure of adolescent girls (n=15) was examined during different phases of their menstrual cycle (follicular, ovulation, and luteal). Blood pressure was monitored with an auto-cuff automatic outpatient blood pressure monitor. Investigation showed gender-related differences in 24-h blood pressure. Study results revealed the circadian blood pressure rhythm characterized by a period of low values during nighttime and an early morning increase in both adolescent groups. Nocturnal systolic blood pressure was higher (P<0.05) in boys than in girls in all phases of their menstrual cycle. Diurnal systolic blood pressure in boys was higher than in girls in their follicular phase (P<0.05). The day and night blood pressure differed between boys and girls (P<0.05). A dipping blood pressure pattern as a decrease in mean nighttime blood pressure as compared with mean daytime blood pressure was defined: 10.02+/-6.7% in girls (n=22) and 13+/-6.3% in boys (n=22), without gender-related differences (P>0.05). There were no differences in blood pressure dipping among girls' groups in different menstrual cycle phases (P>0.05). Adolescent boys showed a significant positive correlation between their mean diurnal blood pressure and height (P<0.05). The study proved gender-related arterial blood pressure differences in healthy adolescents. The results demonstrate the gender-specific circadian blood pressure rhythm pattern in both gender groups.

Effects of Continuous Positive Airway Pressure Treatment and Withdrawal in Patients With Obstructive Sleep Apnea on Arterial Stiffness and Central BP*

Obstructive sleep apnea (OSA) is associated with increased BP and other cardiometabolic risk factors. The aim of the present study was to determine whether arterial stiffness and central BP (two important cardiovascular risk factors) would change, independent of peripheral BP following either the initiation of or withdrawal from nasal continuous positive airway pressure (CPAP) treatment in subjects with OSA. Arterial stiffness and peripheral and central BP were measured at baseline, and then either at 2 months after starting CPAP therapy (intervention group, n=20) or 7 nights after withdrawal from CPAP therapy (withdrawal group, n=20) using pulse wave analysis. In the intervention group, there were reductions in arterial stiffness (ie, the aortic augmentation index fell by 2.5%) and central systolic BP (fell by 4.2 mm Hg) without a concomitant reduction in peripheral BP. The change in arterial stiffness was associated with CPAP compliance (r=-0.47). In contrast, in the withdrawal group there were no overall changes in arterial stiffness or BP. However, there was an early morning increase in diastolic BP and heart rate relative to late evening. These results suggest that clinically important changes in arterial stiffness and central BP may occur following effective CPAP treatment of OSA without parallel changes in peripheral BP.

Seasonal and diel variation of atmospheric mercury concentrations in the Reno (Nevada, USA) airshed

This paper describes total gaseous mercury (TGM) concentrations measured in Reno, Nevada from 2002 to 2005. The 3-year mean and median air Hg concentrations were 2.3 and 2.1 ng m −3, respectively. Mercury concentrations exhibited seasonality, with the highest concentrations in winter, and the lowest in summer and fall. A well-defined diel pattern in TGM concentration was observed, with maximum daily concentrations observed in the morning and minimum in the afternoon. A gradual increase of TGM concentration was observed in the evening and over night. The early morning increase in TGM was likely due to activation of local surface emission sources by rising solar irradiance and air temperature. The subsequent decline and afternoon minimum in TGM were likely related to increased vertical mixing and the buildup of atmospheric oxidants during the day resulting in increased conversion to oxidized species that are quickly deposited, coupled with weakening of the surface emissions processes. The described diel pattern was seasonally modulated with the greatest amplitude in variation of TGM concentrations occurring in the summer. It is suggested based on the comparison of diel TGM pattern with other gaseous pollutants that natural source surface emissions are a dominant source of TGM in the study area.