bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonproteolytic Activation of Prorenin Contributes to Development of Cardiac Fibrosis in Genetic Hypertension
Authors: Ichihara Atsuhiro , Kaneshiro Yuki , Takemitsu Tomoko , Sakoda Mariyo , Suzuki Fumiaki , Nakagawa Tsutomu , Nishiyama Akira , Inagami Tadashi , Hayashi Matsuhiko
Published: April 2006

In contrast to proteolytic activation of inactive prorenin by cleavage of the N-terminal 43 residue peptide, we found that prorenin is activated without proteolysis by binding of the prorenin receptor to the pentameric “handle region” I
11P
LLKK
15P
. We hypothesized that such activation occurs in hypertensive rats and causes cardiac renin–angiotensin system (RAS) activation and end-organ damage. To test this hypothesis, we devised methods of specifically inhibiting nonproteolytic activation by decapeptide spanning the pentameric handle region peptide as a decoy. In stroke-prone spontaneously hypertensive rats (SHRsp) fed a high-salt diet, arterial pressure started to rise significantly with a marked increase in the cardiac prorenin receptor mRNA level at 8 weeks of age, and cardiac fibrosis had developed by 12 weeks of age. By immunohistochemistry using antibodies to the active site of the renin molecule, we demonstrated increased proteolytic or nonproteolytic activation of prorenin in the heart but not in plasma of SHRsp. Continuous subcutaneous administration of the handle region peptide completely inhibited the increased staining by antibodies to the active site of the renin molecule, indicating the increased nonproteolytic but not proteolytic activation of prorenin in the heart of SHRsp. Administration of the handle region peptide also inactivated tissue RAS without affecting circulating RAS or arterial pressure and significantly attenuated the development and progression of cardiac fibrosis. These results clearly demonstrate the significant role of nonproteolytically activated tissue prorenin in tissue RAS activation leading to cardiac fibrosis and significant inhibition of the cardiac damage produced by chronic infusion of the handle region peptide.
Longitudinal Mitral Annulus Velocities Are Reduced in Hypertensive Subjects With or Without Left Ventricle Hypertrophy
Authors: Borges Maria Cândida C. , Colombo Roberta C.R. , Gonçalves José Geraldo F. , Ferreira José de Oliveira , Franchini Kleber G.
Published: April 2006

Normotensive and hypertensive subjects with and without left ventricular (LV) hypertrophy (LV mass index [LVMI] >51 g/m
2.7
) were examined by conventional echocardiography and tissue Doppler imaging of mitral annulus motion. The subgroups included nonobese normotensive subjects (n=16; age 51±9 years; 11 female; systolic blood pressure [SBP] 109±11 mm Hg, body mass index [BMI] 24±2.7 kg/m
2
; LVMI 32±5.5 g/m
2.7
), nonobese hypertensive subjects without LV hypertrophy (n=16; age 54±12 years; 12 female; SBP 166±15 mm Hg; BMI 25±2.7 kg/m
2
; LVMI 42±5.5 g/m
2.7
), and hypertensive subjects with LV hypertrophy (n=22; age 56±10 years; 10 female; SBP 181±19 mm Hg; BMI 26±2.3 kg/m
2
; LVMI 69±16 g/m
2.7
). Ejection fraction was comparable among the subgroups, but midwall fractional shortening was reduced in hypertensive subjects with LV hypertrophy (≈26%). Isovolumic relaxation time was increased in subjects with LV hypertrophy, whereas mitral wave A velocity was increased in hypertensive subjects with and without LV hypertrophy. Tissue Doppler imaging mitral annulus systolic (S
M
) and diastolic (E
M
) velocities were reduced in subjects with and without LV hypertrophy compared with normotensive subjects. There was a positive correlation between S
M
and E
M
(
r
=0.68;
P
<0.0001) and negative correlations between these 2 variables and LVMI (S
M
,
r
=−0.41;
P
=0.002; E
M
,
r
=−0.56;
P
<0.0001). Thus, reductions in mitral annulus systolic and diastolic velocities parallel increases in LV mass in hypertensive subjects, beginning at LV mass within the clinically defined normal values.
Abnormalities of Retinal Microvascular Structure and Risk of Mortality From Ischemic Heart Disease and Stroke
Authors: Witt Nicholas , Wong Tien Y. , Hughes Alun D. , Chaturvedi Nish , Klein Barbara E. , Evans Richard , McNamara Mary , Thom Simon A. McG , Klein Ronald
Published: April 2006

Abnormalities of the retinal microcirculation are found in hypertension and diabetes and predict cardiovascular mortality. This study examined the relationship between abnormalities of the retinal microvasculature and death from ischemic heart disease (IHD) and stroke. A population-based, nested case-control study was undertaken within the Beaver Dam Eye Study. Subjects (43 to 74 years) who died of IHD (n=126) or stroke (n=28) over a 10-year period were age and gender matched with controls subjects (n=528; case:control matching, ≈1:4). Retinal photographs of cases and controls were digitized and analyzed using a computer-based technique. Increased risk of IHD death was associated with a suboptimal relationship of arteriolar diameters at bifurcation (
P
=0.02 unadjusted) and decreased retinal arteriolar tortuosity (
P
=0.011 unadjusted). These associations remained significant after adjustment for age, sex, past history of cardiovascular disease, and other known cardiovascular risk factors. Increased arteriolar length:diameter ratio, a measure of generalized arteriolar narrowing, was associated with increased stroke mortality (
P
=0.02 unadjusted). This association was independent of age and gender but was attenuated by adjustment for systolic blood pressure (
P
=0.15). Other quantitative measures of the retinal microvascular network (eg, venular tortuosity and arteriolar and venular bifurcation angle) were not associated with death from IHD or stroke. Retinal microvascular abnormalities are predictive of death from IHD and stroke. A detailed assessment of the retinal microvascular network from digitized photographs may be useful in the noninvasive assessment of target organ damage and cardiovascular risk.
Different Impact of the Metabolic Syndrome on Left Ventricular Structure and Function in Hypertensive Men and Women
Authors: Schillaci Giuseppe , Pirro Matteo , Pucci Giacomo , Mannarino Massimo R. , Gemelli Fabio , Siepi Donatella , Vaudo Gaetano , Mannarino Elmo
Published: April 2006

Metabolic syndrome (MS) is increasingly recognized as an important cardiovascular risk factor in hypertension, but its influence on left ventricular (LV) mass and function in the 2 genders has not been specifically addressed. Among 618 nondiabetic, untreated hypertensive subjects, echocardiographically detected LV mass was significantly greater in subjects with MS. A significant interaction was observed between sex and the MS (
P
<0.003 for the multiplicative interaction term). Compared with women without the MS, those with the syndrome had a 24% greater LV mass (49.5±12 versus 40.0±10 g×m
−2.7
;
P
<0.001), whereas the difference was only 9% in men (50.3±12 versus 46.1±10 g×m
−2.7
;
P
=0.003). A greater prevalence of LV hypertrophy was found in women (37% versus 14%;
P
<0.001) but not in men (39% versus 29%;
P
=0.09) with the MS. After adjustment for the effect of age, body mass index, 24-hour systolic blood pressure, and several confounders, the MS was independently associated with a greater LV mass index in women (regression coefficient, 4.80;
P
<0.001) but not in men. Women with the MS also had a greater LV relative wall thickness (0.42±0.07 versus 0.39±0.07;
P
=0.004) and a depressed afterload-corrected midwall fractional shortening (94.0±12% versus 101.0±13%;
P
<0.001) than women without the syndrome, whereas no differences emerged in men. We conclude that, in untreated hypertension, MS has a different impact on LV hypertrophy and function in men and women. The effect of MS is more pronounced in women and is partly independent from the effect of several hemodynamic and nonhemodynamic determinants of LV mass.
Amino-Terminal Pro-B-Type Natriuretic Peptide and B-Type Natriuretic Peptide
Authors: McKie Paul M. , Rodeheffer Richard J. , Cataliotti Alessandro , Martin Fernando L. , Urban Lynn H. , Mahoney Douglas W. , Jacobsen Steven J. , Redfield Margaret M. , Burnett John C.
Published: April 2006

Recent studies report that, in the absence of heart failure and renal failure, plasma B-type natriuretic peptide (BNP) has prognostic value for mortality. We sought to confirm and extend these previous studies to assess BNP, measured by 3 distinct assays, as a biomarker for mortality in a strategy to enhance efforts at primary prevention and to better understand the clinical phenotype of such subjects at risk. We used a community-based cohort of 2042 subjects from Olmsted County, Minn, and individuals with heart or renal failure were excluded. BNP was assessed using 3 assays including Biosite and Shionogi for mature, biologically active BNP and the Roche assay for apparently nonbiologically active amino-terminal pro-BNP (NT-proBNP). Thorough echocardiographic and clinical data were recorded for all of the participants. Median follow-up for mortality was 5.6 years. BNP by all 3 of the assays was predictive of mortality. NT-proBNP and Biosite assays remained significant even after adjustment for traditional clinical risk factors and echocardiographic abnormalities including left ventricular hypertrophy and diastolic dysfunction. Echocardiography documented widespread structural changes in those with increasing BNP levels yet below levels observed in heart failure. We report in a large, well-characterized community-based cohort, free of heart failure, the first study to compare 3 distinct BNP assays as biomarkers for mortality in the same cohort. Our findings confirm the potential use of NT-proBNP and BNP biomarkers for future events and underscore that these peptides may also serve as biomarkers for underlying cardiac remodeling secondary to diverse cardiovascular disease entities.
Effects of Continuous Positive Airway Pressure Versus Supplemental Oxygen on 24-Hour Ambulatory Blood Pressure
Authors: Norman Daniel , Loredo José S. , Nelesen Richard A. , Ancoli-Israel Sonia , Mills Paul J. , Ziegler Michael G. , Dimsdale Joel E.
Published: April 2006

Obstructive sleep apnea (OSA) is associated with recurrent episodes of nocturnal hypoxia and increased risk for development of systemic hypertension. Prior studies have been limited, however, in their ability to show reduction in blood pressure after continuous positive airway pressure (CPAP) therapy, and the effect of supplemental oxygen alone on blood pressure in OSA has not been evaluated. We performed a randomized, double-blind, placebo-controlled study comparing the effects of 2 weeks of CPAP versus sham-CPAP versus supplemental nocturnal oxygen on 24-hour ambulatory blood pressure in 46 patients with moderate-severe OSA. We found that 2 weeks of CPAP therapy resulted in a significant reduction in daytime mean arterial and diastolic blood pressure and nighttime systolic, mean, and diastolic blood pressure (all
P
s <0.05). Although nocturnal supplemental oxygen therapy improved oxyhemoglobin saturation, it did not affect blood pressure. We conclude that CPAP therapy reduces both daytime and nighttime blood pressure in patients with OSA, perhaps through mechanisms other than improvement of nocturnal oxyhemoglobin saturation.
Short Sleep Duration as a Risk Factor for Hypertension
Authors: Gangwisch James E. , Heymsfield Steven B. , Boden-Albala Bernadette , Buijs Ruud M. , Kreier Felix , Pickering Thomas G. , Rundle Andrew G. , Zammit Gary K. , Malaspina Dolores
Published: April 2006

Depriving healthy subjects of sleep has been shown to acutely increase blood pressure and sympathetic nervous system activity. Prolonged short sleep durations could lead to hypertension through extended exposure to raised 24-hour blood pressure and heart rate, elevated sympathetic nervous system activity, and increased salt retention. Such forces could lead to structural adaptations and the entrainment of the cardiovascular system to operate at an elevated pressure equilibrium. Sleep disorders are associated with cardiovascular disease, but we are not aware of any published prospective population studies that have shown a link between short sleep duration and the incidence of hypertension in subjects without apparent sleep disorders. We assessed whether short sleep duration would increase the risk for hypertension incidence by conducting longitudinal analyses of the first National Health and Nutrition Examination Survey (
n
=4810) using Cox proportional hazards models and controlling for covariates. Hypertension incidence (
n
=647) was determined by physician diagnosis, hospital record, or cause of death over the 8- to 10-year follow-up period between 1982 and 1992. Sleep durations of ≤5 hours per night were associated with a significantly increased risk of hypertension (hazard ratio, 2.10; 95% CI, 1.58 to 2.79) in subjects between the ages of 32 and 59 years, and controlling for the potential confounding variables only partially attenuated this relationship. The increased risk continued to be significant after controlling for obesity and diabetes, which was consistent with the hypothesis that these variables would act as partial mediators. Short sleep duration could, therefore, be a significant risk factor for hypertension.
Influence of Preoperative Left Ventricular Contractile Reserve on Postoperative Ejection Fraction in Low-Gradient Aortic Stenosis
Authors: Quere Jean-Paul , Monin Jean-Luc , Levy Franck , Petit Hélène , Baleynaud Serge , Chauvel Christophe , Pop Camélia , Ohlmann Patrick , Lelguen Claude , Dehant Patrick , Gueret Pascal , Tribouilloy Christophe
Published: April 2006

Background—

Dobutamine stress hemodynamics (DSH) has the potential to stratify operative risk in low-gradient aortic stenosis (AS), but little is known about the relation between left ventricle contractile reserve and postoperative left ventricular ejection fraction (LVEF). We sought to assess the value of DSH to predict postoperative improvement in LVEF.

Methods and Results—

Sixty-six consecutive patients with symptomatic severe AS (aortic valve area ≤1 cm
2
), LVEF ≤40%, and mean pressure gradient ≤40 mm Hg prospectively enrolled in the French multicenter study on low-gradient AS and who survived to aortic valvular replacement (AVR) were included. Preoperative contractile reserve was present in 46 patients (group I; 70%) and absent in 20 patients (group II; 30%). In the overall sample, 58% of patients improved by 2 New York Heart Association (NYHA) classes after AVR. Mean LVEF improved from 29±6% to 47±11% (
P
<0.0001). LVEF improved by ≥10 EF units in 38 patients (83%) in group I and in 13 patients (65%) in group II. Mean LVEF improvement was similar in the 2 groups (19±10% versus 17±11%;
P
=0.54). On multivariable analysis, multivessel coronary artery disease (
P
=0.05) and baseline mean transaortic pressure gradient (
P
=0.01) were related to LVEF improvement, whereas contractile reserve was not.

Conclusions—

LVEF increases in the majority of patients with low-gradient AS who survive after AVR. Although the absence of contractile reserve on DSH is related to high operative mortality, it does not predict the absence of LVEF recovery in patients surviving to AVR. These data further support the concept that surgery should not be contraindicated on the basis of absence of contractile reserve alone.
Role of p90 Ribosomal S6 Kinase–Mediated Prorenin-Converting Enzyme in Ischemic and Diabetic Myocardium
Authors: Itoh Seigo , Ding Bo , Shishido Tetsuro , Lerner-Marmarosh Nicole , Wang Nadan , Maekawa Naoya , Berk Bradford C. , Takeishi Yasuchika , Yan Chen , Blaxall Burns C. , Abe Jun-ichi
Published: April 2006

Background—

Epidemiological data strongly indicate that diabetes increases the incidence of heart failure. Although the benefit of angiotensin-converting enzyme inhibitor (ACE-I) treatment during and after myocardial infarction has been found to be greater in diabetics than nondiabetics and activation of the renin-angiotensin system (RAS) has been implicated, the molecular basis of these actions remains unclear.

Methods and Results—

We generated transgenic mice with cardiac-specific overexpression of wild-type p90 ribosomal S6 kinase (WT-p90RSK-Tg) and a dominant-negative form of p90RSK (DN-p90RSK-Tg). Recovery of cardiac function after ischemia/reperfusion in WT-p90RSK-Tg isolated mouse hearts was significantly impaired. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed specific induction of prorenin-converting enzyme (PRECE) in WT-p90RSK-Tg mice. mRNA induction of PRECE was confirmed with serial angiotensinogen protein reduction after perfusion in WT-p90RSK-Tg mice, suggesting an increase of angiotensinogen cleavage and subsequent RAS activation in WT-p90RSK-Tg mice. We investigated the role of the RAS in WT-p90RSK-Tg animals after ischemia/reperfusion with the use of an ACE-I (captopril) and an angiotensin II type 1 receptor blocker (olmesartan). We did not observe any effect of these inhibitors in non-Tg littermate controls, thus corroborating other reports in rodents. In contrast, both captopril and olmesartan significantly improved cardiac function and reduced infarct size in WT-p90RSK-Tg mice. At 8 months of age, WT-p90RSK-Tg mice developed cardiac dysfunction. p90RSK activity and PRECE mRNA were both increased by streptozotocin-induced hyperglycemia in non-Tg littermate controls, whereas DN-p90RSK-Tg animals exposed to streptozotocin did not have PRECE induction.

Conclusions—

This study demonstrates the critical role of p90RSK in hyperglycemia-mediated myocardial PRECE induction, which may explain the augmentation of the RAS in diabetic hearts and provide an alternative therapeutic approach to treat diabetic cardiomyopathy.
Modeling the Evolution of the Atmospheric Boundary Layer Coupled to the Land Surface for Three Contrasting Nights in CASES-99
Authors: Steeneveld G. J. , van de Wiel B. J. H. , Holtslag A. A. M.
Published: April 2006

The modeling and prediction of the stable boundary layer over land is a persistent, problematic feature in weather, climate, and air quality topics. Here, the performance of a state-of-the-art single-column boundary layer model is evaluated with observations from the 1999 Cooperative Atmosphere–Surface Exchange Study (CASES-99) field experiment. Very high model resolution in the atmosphere and the soil is utilized to represent three different stable boundary layer archetypes, namely, a fully turbulent night, an intermittently turbulent night, and a radiative night with hardly any turbulence (all at clear skies). Each archetype represents a different class of atmospheric stability. In the current model, the atmosphere is fully coupled to a vegetation layer and the underlying soil. In addition, stability functions (local scaling) are utilized based on in situ observations.

Overall it is found that the vertical structure, the surface fluxes (apart from the intermittent character) and the surface temperature in the stable boundary layer can be satisfactorily modeled for a broad stability range (at a local scale) with the current understanding of the physics of the stable boundary layer. This can also be achieved by the use of a rather detailed coupling between the atmosphere and the underlying soil and vegetation, together with high resolution in both the atmosphere and the soil. This is especially true for the very stable nights, when longwave radiative cooling is dominant. Both model outcome and observations show that in the latter case the soil heat flux is a dominant term of the surface energy budget.
Sensitivity Studies of the Importance of Dust Ice Nuclei for the Indirect Aerosol Effect on Stratiform Mixed-Phase Clouds
Authors: Lohmann U. , Diehl K.
Published: April 2006

New parameterizations of contact freezing and immersion freezing in stratiform mixed-phase clouds (with temperatures between 0° and −35°C) for black carbon and mineral dust assumed to be composed of either kaolinite (simulation KAO) or montmorillonite (simulation MON) are introduced into the ECHAM4 general circulation model. The effectiveness of black carbon and dust as ice nuclei as a function of temperature is parameterized from a compilation of laboratory studies. This is the first time that freezing parameterizations take the chemical composition of ice nuclei into account. The rather subtle differences between these sensitivity simulations in the present-day climate have significant implications for the anthropogenic indirect aerosol effect. The decrease in net radiation in these sensitivity simulations at the top of the atmosphere varies from 1 ± 0.3 to 2.1 ± 0.1 W m−2 depending on whether dust is assumed to be composed of kaolinite or montmorillonite. In simulation KAO, black carbon has a higher relevancy as an ice nucleus than in simulation MON, because kaolinite is not freezing as effectively as montmorillonite. In simulation KAO, the addition of anthropogenic aerosols results in a larger ice water path, a slightly higher precipitation rate, and a reduced total cloud cover. On the contrary, in simulation MON the increase in ice water path is much smaller and globally the decrease in precipitation is dominated by the reduction in warm-phase precipitation due to the indirect cloud lifetime effect.
A Method to Estimate Aerosol Radiative Forcing from Spectral Optical Depths
Authors: Satheesh S. K. , Srinivasan J.
Published: April 2006

Radiative forcing of aerosols is much more difficult to estimate than that of well-mixed gases due to the large spatial variability of aerosols and the lack of an adequate database on their radiative properties. Estimation of aerosol radiative forcing generally requires knowledge of its chemical composition, which is sparse. Ground-based sky radiance measurements [e.g., aerosol robotic network (AERONET)] can provide key parameters such as the single-scattering albedo, but in shipborne experiments over the ocean it is difficult to make sky radiance measurements and hence these experiments cannot provide parameters such as the single-scattering albedo. However, aerosol spectral optical depth data (cruise based as well as satellite retrieved) are available quite extensively over the ocean. Spectral optical depth measurements have been available since the 1970s, and spectral turbidity measurements (carried out at meteorological departments all over the world) have been available for several decades, while long-term continuous chemical composition information is not available. A new method to differentiate between scattering and absorbing aerosols is proposed here. This can be used to derive simple aerosol models that are optically equivalent and can simulate the observed aerosol optical properties and radiative fluxes, from spectral optical depth measurements. Thus, aerosol single-scattering albedo and, hence, aerosol radiative forcing can be estimated. Note that the proposed method is to estimate clear-sky aerosol radiative forcing (over regions where chemical composition data or sky radiance data are not available) and not to infer its exact chemical composition. Using several independent datasets from field experiments, it is demonstrated that the proposed method can be used to estimate aerosol radiative forcing (from spectral optical depths) with an accuracy of ±2 W m−2.
Origin of the Summertime Synoptic-Scale Wave Train in the Western North Pacific*
Authors: Li Tim
Published: April 2006

The origin of the summertime synoptic wave train in the western North Pacific is investigated with a multilevel, nonlinear baroclinic model. A realistic three-dimensional summer mean state is specified and eigenvectors are calculated by introducing small perturbation initially to the model. Numerical experiments indicate that the origin of the synoptic wave train may arise from instability of the summer mean flow in the presence of a convection–frictional convergence (CFC) feedback. In the lack of the CFC feedback, the summer mean flow supports only a least damped mode, characterized by a northwest–southeast-oriented wave train pattern with a zonal wavelength of 2500 km. In the presence of both the realistic summer mean flow and the CFC feedback, the model reproduces a fast growing mode, whose structure and propagation characters are similar to the observed.

Sensitivity experiments with different initial perturbation patterns indicate that the model solution is not sensitive to initial conditions. Further sensitivity experiments reveal that the basic-state vertical shear may affect the growth rate and propagation character of the wave train. An easterly shear may lead to a faster growth and northwestward phase propagation, whereas a westerly shear may favor a slower growth and southeastward phase propagation.
Seasonal Hydroclimate Variability over North America in Global and Regional Reanalyses and AMIP Simulations: Varied Representation
Authors: Nigam Sumant , Ruiz-Barradas Alfredo
Published: April 2006

The monotony of seasonal variability is often compensated by the complexity of its spatial structure—the case in North American hydroclimate. The structure of hydroclimate variability is analyzed to provide insights into the functioning of the climate system and climate models.

The consistency of hydroclimate representation in two global [40-yr ECMWF Re-Analysis (ERA-40) and NCEP] and one regional [North American Regional Reanalysis (NARR)] reanalysis is examined first, from analysis of precipitation, evaporation, surface air temperature (SAT), and moisture flux distributions. The intercomparisons benchmark the recently released NARR data and provide context for evaluation of the simulation potential of two state-of-the-art atmospheric models [NCAR's Community Atmospheric Model (CAM3.0) and NASA's Seasonal-to-Interannual Prediction Project (NSIPP) atmospheric model].

Intercomparisons paint a gloomy picture: great divergence in global reanalysis representations of precipitation, with the eastern United States being drier in ERA-40 and wetter in NCEP in the annual mean by up to a third in each case; model averages are like ERA-40. The annual means, in fact, mask even larger but offsetting seasonal departures.

Analysis of moisture transport shows winter fluxes to be more consistently represented. Summer flux convergence over the Gulf Coast and Great Plains, however, differs considerably between global and regional reanalyses. Flux distributions help in understanding the choice of rainy season, especially the winter one in the Pacific Northwest; stationary fluxes are key.

Land–ocean competition for convection is too intense in the models—so much so that the oceanic ITCZ in July is southward of its winter position in the both simulations! The overresponsiveness of land is also manifest in SAT; the winter-to-summer change over the Great Plains is 5–9 K larger than in observations, with implications for modeling of climate sensitivity.

The nature of atmospheric water balance over the Great Plains is probed, despite unbalanced moisture budgets in reanalyses and model simulations. The imbalance is smaller in NARR but still unacceptably large, resulting from excessive evaporation in spring and summer. Adjusting evaporation during precipitation assimilation could lead to a more balanced budget.

Global and regional reanalysis will remain of limited use for hydroclimate studies until they comply with the operative water and energy balance constraints.
Observed Vegetation–Climate Feedbacks in the United States*
Authors: Notaro M. , Liu Z. , Williams J. W.
Published: April 2006

Observed vegetation feedbacks on temperature and precipitation are assessed across the United States using satellite-based fraction of photosynthetically active radiation (FPAR) and monthly climate data for the period of 1982–2000. This study represents the first attempt to spatially quantify the observed local impact of vegetation on temperature and precipitation over the United States for all months and by season. Lead–lag correlations and feedback parameters are computed to determine the regions where vegetation substantially impacts the atmosphere and to quantify this forcing. Temperature imposes a significant instantaneous forcing on FPAR, while precipitation's impact on FPAR is greatest at one-month lead, particularly across the prairie. An increase in vegetation raises the surface air temperature by absorbing additional radiation and, in some cases, masking the high albedo of snow cover. Vegetation generally exhibits a positive forcing on temperature, strongest in spring and particularly across the northern states. The local impact of FPAR on precipitation appears to be spatially inhomogeneous and relatively weak, potentially due to the atmospheric transport of transpired water. The computed feedback parameters can be used to evaluate vegetation–climate interactions simulated by models with dynamic vegetation.
Prevention of Recurrent Deep Venous Thrombosis with Sulodexide: The SanVal Registry
Authors: Errichi B. M. , Cesarone M. R. , Belcaro G. , Marinucci R. , Ricci A. , Ippolito A. , Brandolini R. , Vinciguerra G. , Dugall M. , Felicita A. , Pellegrini L. , Gizzi G. , Ruffini M. , Acerbi G. , Bavera P. , Di Renzo A. , Corsi M. , Scoccianti M. , Hosoi M. , Lania M.
Published: April 2006

The aim of this study was to evaluate the prevention of recurrent deep vein thrombosis (RDVT) with an oral antithrombotic agent (sulodexide) in moderate to high-risk subjects. A group of 405 patients was included into the multicenter registry. Both compression and an exercise program were used as well as a risk-factors control plan. After diagnosis of DVT, patients were treated with oral anticoagulants for 6 months. At the end of this period a coagulation study was made and patients started treatment with oral sulodexide capsules for a period of 24 months. The femoral, popliteal, tibial, and superficial veins were scanned with high-resolution ultrasound at inclusion; scans were repeated at 6, 12, 18, and 24 months. Of the 405 subjects included into the registry 178 in the control group (mean age 52.2; SD 11; M:F = 90:88) and 189 in the treatment group (mean age 53.2; SD 10.3; M:F = 93:96) completed the analysis period of 24 months. At 6 and 12 months the incidence of R-DVT was lower (p<0.05) in the treatment group. At 24 months the global incidence of R-DVT was 17.9% in the control group and 7.4% in the sulodexide group (p<0.05), 2.42 times lower than in controls. The 2 groups were comparable for age and sex distribution and for the localization of the thrombi at inclusion. Also the 2 groups of dropouts were comparable. In the control group there were 32 recurrent DVTs and 24 subjects lost to follow-up (total of 56) of 202 included subjects (27.7%) in comparison with 28 failures (14 recurrent DVTs and 14 lost subjects) of 203 subjects (13.8%) in the treatment group. This difference was statistically significant. In this analysis the incidence of DVT in controls was 2.07 times higher than in the treatment group subjects. In conclusion sulodexide was effective in reducing recurrent thrombotic events in high-risk subjects.
Surveillance Versus Nonsurveillance for Femoro-Popliteal Bypass Grafts
Authors: Fasih T. , Rudol G. , Ashour H. , Mudawi A. , Bhattacharya V.
Published: April 2006

This is a study of 97 patients who underwent 106 femoropopliteal bypass grafts (9 bilateral bypasses) for short-distance claudication and critical ischemia. Patients were divided into 2 groups. The first group (n=64) was followed up by use of duplex scans. The second group (n=42) was followed up in clinic without duplex surveillance. Twenty-three patients from the surveillance group developed stenoses of the grafts. Of these, 14 underwent successful angioplasty. A total of 43 grafts became blocked. Graft occlusion was significantly more common in the nonsurveillance group (n=29) as compared to the surveillance group (n=14) after both 1 and 3 years of observation (p=0.001). Patients with critical ischemia showed a higher rate of graft occlusion than the claudicants (p=0.0075). Sixteen patients in the nonsurveillance group underwent above/below-knee amputation compared to 1 in the surveillance group. There was no significant difference in the mortality rate in the 2 groups. Graft surveillance helped to improve patency of grafts by identifying the correctable lesions.
Carotid Atherosclerosis is Correlated with Extent and Severity of Coronary Artery Disease Evaluated by Myocardial Perfusion Scintigraphy
Authors: Hallerstam Staffan , Larsson P. Thomas , Zuber Ernst , Rosfors Stefan
Published: April 2006

Increased intima-media thickness (IMT) in the common carotid artery (CCA) correlates with conventional risk factors for cardiovascular disease and is an independent predictor of cardiac events. However, correlation between IMT and degree of ischemic heart disease evaluated by coronary angiogram is weak. The purpose of this study was to investigate the relationship between measures of carotid atherosclerosis and the extent and severity of coronary artery disease (CAD) in 111 consecutive patients (60 men and 51 women, mean age 60 years) with known or suspected CAD who were investigated with adenosine-stress myocardial perfusion scintigraphy. Common carotid artery lumen diameter (LD) and IMT of the carotid bulb and distal CCA were measured with ultrasound, and CCA cross-sectional intima-media area (CIMA) was calculated. Seventy-two of 110 patients (65%) had significant perfusion defects. Increasing carotid plaque occurrence (absence, unilateral or bilateral occurrence) correlated with more advanced CAD (p<0.01). The extent and severity of myocardial hypoperfusion correlated significantly with presence of carotid plaque ( r =0.23 and 0.24 respectively, p<0.05), CIMA ( r =0.23 and 0.22, p<0.05), and LD ( r =0.26 and 0.25, p<0.01) but not with IMT. In contrast to CIMA, LD failed to show an independent relation to extent of CAD after adjustment for age, sex, and body mass index. In conclusion, in subjects with intermediate to high risk of ischemic heart disease, occurrence of carotid plaques and increased cross-sectional intima-media area in the common carotid artery are the best parameters for predicting CAD expressed as myocardial hypoperfusion.
Atherogenic Effect of Interleukin-2 and Antiatherogenic Effect of Interleukin-2 Antibody in Apo-E-Deficient Mice
Authors: Upadhya Subramanya , Mooteri Shanthalaxmi , Peckham Norman , Pai Ramdas G.
Published: April 2006

Growing evidence suggests that atherosclerosis is an immune-mediated inflammatory process and that cytokines participate as mediators in this process. Of the cytokines, interleukins, which are released from both immune and nonimmune cells of vascular wall, are found to have multiple effects. Interleukin-2 (IL-2), a cytokine produced by activated T-lymphocytes, has been found to further activate the T cells and may potentially enhance atherogenesis. Apo-E-deficient mice fed with atherogenic diet were injected intraperitoneally twice a week with placebo, IL-2, or anti-IL-2 antibody for a period of 6 weeks. Group 1 (n=6) was injected with bovine serum albumin (BSA) in phosphate-buffered saline (PBS) and served as controls. Group 2 (n=6) was injected with 2x104 units of recombinant murine IL-2 (rmIL-2) per dose reconstituted with BSA in PBS. Group 3 (n=6) was injected with 5 µg of anti-IL-2 per dose reconstituted with BSA in PBS. Aortic sections were analyzed and atherosclerotic burden was quantified. Compared to controls, injection of IL-2 increased measures of atherosclerosis such as the average lesion score (10.7 ±0.5 vs 9.3 ±1.1, p=0.04) and the lesion size as a fraction of aortic area (0.51 ±0.03 vs 0.41 ±0.05, p=0.01). Injection of anti-IL-2 had a profound antiatherogenic effect. It significantly reduced the average number of lesions per cross section (2.6 ±0.6 vs 4.3 ±0.6, p=0.03), the average lesion score (4.6 ±1.9 vs 9.3 ±1.1, p=0.02), the lesion area/circumference (0.35 ±0.08 vs 0.62 ±0.10, p=0.007), and the lesion size/aortic area (0.23 ±0.07 vs 0.41 ±0.05, p=0.03). These results indicate that IL-2 is an atherogenic cytokine in apo-E-deficient mice and anti-IL-2 is protective against atherosclerosis. This may have important clinical implications in modifying the atherosclerotic process.
The Effect of Dobutamine Stress on Left Ventricular Outflow Tract Gradients in Hypertensive Patients with Basal Septal Hypertrophy
Authors: Yalçin Fatih , Muderrisoglu Haldun , Korkmaz Mehmet Emin , Ozin Bulent , Baltali Mehmet , Yigit Fatma
Published: April 2006

Basal septal hypertrophy (BSH), a cause of left ventricular outflow tract (LVOT) obstruction, is thought to occur by increased ventricular dynamics. The aim of the study was to evaluate the effect of pharmacologic stress on LVOT gradients in a group of hypertensive patients with BSH. Dobutamine stress was used in 24 hypertensive patients (mean age 56 ±8 years; 11 women) with BSH and 20 normal controls (mean age 54 ±9 years; 7 women). Ejection fraction and myocardial mass, basal septal dimension, and LVOT diameter were measured with 2-dimensional echocardiography. LVOT velocities and transmitral velocities before and at peak dobutamine infusion were determined by continuous wave Doppler and pulsed Doppler, respectively. There were no differences in mean ejection fraction and myocardial mass between BSH patients (58 ±3%, 204 ±24 g) and normals (56 ±4%, 201 ±32 g). The basal septum was thicker in patients (1.55 ±0.2 cm) than in normals (1.03 ±0.1 cm, p<0.001). Maximum LVOT velocities were similar in BSH (1.2 ±0.4 m/sec) and normals (1.1 ±0.2 m/sec) at rest. At peak stress, maximum LVOT velocities were higher in BSH (3.3 ±0.6 m/sec) than normals (1.7 ±0.4 m/sec, p<0.001). LV rate-pressure product at peak stress was higher in BSH (23,326 ±4,388) than normals (17,592 ±2,409, p<0.001). LV isovolumetric relaxation time was prolonged, and the E/A ratio was decreased in the patients at rest (130 ±14 msec and 0.72 ±0.18, respectively, p<0.001). At peak stress, diastolic function did not significantly change in two groups. The correlations between LVOT velocity change by stress and mean LVOT diameter ( r =-0.668, p<0.001) and mean BS thickness ( r =0.610; p<0.001) were significant in the whole group. High velocities appeared on LVOT at peak pharmacologic stress in the hypertensive patients with BSH compared with control group. This suggests dynamic ventricular ejection by stress may contribute to hypertrophy of the basal segment, which is the closest part of septum to increased afterload.
The Electrocardiogram in Large Pericardial Effusion: The Forgotten “P” Wave and the Influence of Tamponade, Size, Etiology, and Pericardial Thickness on QRS Voltage
Authors: Habashy Atef G. , Mittal Ashok , Ravichandran Nalini , Cherian George
Published: April 2006

There are varying reports on the electrocardiogram in pericardial effusions. Some correlate low QRS voltage with tamponade and the size of the effusion while others do not. Low voltage also appears to vary with the etiology. There are no reports on the influence of pericardial thickness or changes in the P voltage. The authors studied 43 patients with large effusions of whom 26 had tuberculosis and the remaining had viral/idiopathic etiology. Pericardial thickness was measured at chest computed tomography. They found no correlation between the low QRS voltage and tamponade, size of the effusion, etiology, or pericardial thickness. Low voltage of the P wave and T-wave changes were more frequent than low QRS voltage.
Essential Thrombocythemia-Related Acute ST-Segment Elevation Myocardial Infarction
Authors: Daya Samantapudi K. , Gowda Ramesh M. , Landis William A. , Khan Ijaz A.
Published: April 2006

Essential thrombocythemia is a clonal disorder of the myeloid stem cell that causes pathologic expansion of the megakaryocytic elements in the bone marrow, with a persistent increase in the platelet count. The disease is associated with an elevated risk of thrombosis, hemorrhage, and vasomotor symptoms. The presenting features of essential thrombocythemia can range from being asymptomatic to thrombohemorrhagic complications including acute myocardial infarction. Acute ST-segment elevation myocardial infarction due to left main trunk and ostial left anterior descending coronary artery lesions was diagnosed in a young 31-year-old man. Platelet count was markedly increased and essential thrombocythemia was also diagnosed. Because of left main disease, primary coronary intervention was not feasible and an emergent coronary artery bypass grafting was performed along with pharmacologic management of essential thrombocythemia. The early postoperative period was complicated by acute pulmonary embolism. Hydroxyurea and anagrelide were administered postoperatively, resulting in the decrease of platelet count. A succinct review of myocardial infarction in patients with essential thrombocythemia is presented, and therapeutic strategies in such patients are discussed.
Regression of Achilles Tendon Xanthomas Evaluated by CT Scan After Hypolipidemic Treatment with Simvastatin
Authors: Kolovou Genovefa , Daskalova Deliana , Mastorakou Irene , Anagnostopoulou Katherine , Cokkinos Dennis V.
Published: April 2006

Familial hypercholesterolemia (FH) is a relatively common autosomal monogenic disease with dominant inheritance and threefold to fourfold increase in relative risk of cardiovascular death in untreated patients. For a “definitive” clinical diagnosis of FH the Simon Broome Register proposes the presence of tendon xanthomas as a key feature. However, detection of tendon xanthomas by physical examination is subjective and difficult to use for follow-up purposes. Several instrumental methods have been reported to be more sensitive than physical examination for the evaluation of xanthomas. The present case illustrates the usefulness of computed tomography (CT) to detect xanthomas in the Achilles tendons (XAT) and their regression in response to hypolipidemic drug treatment in a heterozygous FH patient. As XAT are atherosclerotic plaque-like depositions of lipids it is likely that their progression or regression follows the behavior of vascular atherosclerotic lesions.
Recurrent Laryngeal Nerve Injury: A Complication of Central Venous Catheterization
Authors: Salman Mahmoud , Potter Mike , Ethel Mark , Myint Fiona
Published: April 2006

This case report highlights the emergence of new complications associated with old procedures as the frequency of their use increases. A 29-year-old man with aplastic anemia was admitted for a bone marrow transplant. Before this procedure, a Hickman line was inserted. This was followed by hoarseness of voice. An examination revealed an immobile left vocal cord. Further investigations did not show any cause for this complication. Therefore, the hoarseness and vocal cord paralysis was attributed to trauma associated with the insertion of the Hickman line.
The Special Olympics Athlete: Evaluation and Clearance for Participation
Authors: Birrer Richard B.
Published: April 2006

Evaluating and clearing the Special Olympics athlete for participation in sports and recreational activities can be a challenging task for a primary care physician. Radiographic clearance of the cervical spine is mandatory for all athletes with Down syndrome. Regular physical activity for this special population has measurable physiologic and psychosocial benefits.
Update on National Asthma Education and Prevention Program Pediatric Asthma Treatment Recommendations
Authors: Eid Nemr S.
Published: April 2006

The National Asthma Education and Prevention Program (NAEPP) published an update on selected topics from the 1997 Guidelines for the Diagnosis and Management of Asthma and provided new evidence-based recommendations for asthma treatment. Selected topics on the long-term management of asthma in children addressed the efficacy of inhaled corticosteroids (ICSs) compared with other asthma medications (i.e., as-needed β2-adrenergic agonists and other controllers) in mild and moderate persistent asthma and the safety of long-term ICS use. The effects of early intervention with ICSs on asthma progression also were evaluated. An important new aspect of the treatment update entails the recommendation of ICSs as the controller medication of choice for all severities of persistent asthma in children. Additionally, on the basis of studies in adults, the Expert Panel suggested that long-acting β2-adrenergic agonists are now the preferred adjunct to ICSs in children with moderate or severe persistent asthma. Based on long-term data in children, ICS therapy was deemed safe in terms of growth, bone mineral density, ocular effects, and hypothalamic pituitary adrenal axis function. Although members of the NAEPP Expert Panel determined that the effects of early intervention with ICSs on decline in lung function have not been adequately studied, they found that the effects on asthma control were substantial.
A Prospective Study of the “Two-Bag System” in Diabetic Ketoacidosis Management
Authors: Poirier Michael P. , Greer David , Satin-Smith Marta
Published: April 2006

The “two-bag” system, an adaptation of the euglycemic clamp technique, consists of simultaneous administration of 2 intravenous (IV) fluid bags of differing dextrose concentrations. Individualized therapy is dictated by adjustment of the infusion rate of each bag. We sought to assess the benefits of the two-bag system in the initial acute emergency department management of children in diabetic ketoacidosis (DKA). Thirty-three children presenting to an urban pediatric emergency department in DKA were randomized into 2 groups: patients managed with the two-bag system and patients managed with the traditional “one-bag” system. Other aspects of the management were standardized. Outcome measures included rate of decline in serum glucose, rate of bicarbonate correction, time on IV insulin therapy, and response time for IV fluid changes. Study period was defined as time on IV insulin therapy. There were no differences between the 2 groups in demographic parameters, initial baseline metabolic parameters, or total time on IV insulin therapy. There were no differences between the groups in average rates of serum glucose decline: two-bag 33.1 mg/dL/hr (s.e. 5.57, 95% CI 22.2, 44), one-bag 30.2 mg/dL/hr (s.e. 5.72, 95% CI 19, 41.4); average rate of serum bicarbonate correction: two-bag 1.19 mEq/L/hr, one-bag 1.27 mEq/L/hr; or the average number of IV fluid bags used: two-bag 4.1 bags, one-bag 3.2 bags. However, there was a difference between the groups in regard to elapsed total time to make changes in the IV fluids: two-bag 1 minute, one-bag 42 minutes, (p < 0.001). The “two-bag” system enables a faster response time in making IV fluid therapy changes. This efficiency makes this system ideal for use in the emergency department.
Risk Factors for Development of Nontyphoid Salmonella Bacteremia
Authors: Grisaru-Soen Galia , Wysoki Michael G. , Keller Nathan
Published: April 2006

The objective of this paper was to identify risk factors for nontyphoid Salmonella bacteremia by making a retrospective chart review of 39 patients with nontyphoid Salmonella bacteremia. The control group included 30 patients with positive Salmonella stool culture (gastroenteritis group). Demographic factors, presenting signs and symptoms, antimicrobial treatment before admission, and microbiologic results were recorded. Nine patients (23%) were excluded owing to recognized risk factors for development of extraintestinal disease. Seventeen cases (57%) occurred during summer time, whereas the gastroenteritis group had a less seasonal tendency. Eighty percent of the patients with Salmonella bacteremia had a previous history of diarrhea. At admission more patients in the bacteremia group were febrile and had leukocytosis (73% vs 33% and 37% vs 20%, respectively). More patients in the bacteremia group had previous antibiotic treatment (57% vs 20%, p<0.01). The Salmonella types were mainly C and D in the bacteremia group (40% each), and B and C in the gastroenteritis group (26% and 52%, respectively). The risk factors for Salmonella bacteremia in previously healthy children include warm season, previous gastrointestinal illness, and preexposure to antibiotics.